If you played Pokémon Red or Pokémon Blue on a Game Boy, there is a good chance you heard a playground legend that sounded completely fake: “You can make 99 Rare Candies if you talk to an old man, fly to an island, and fight a scrambled-looking Pokémon that definitely was not approved by Professor Oak.” Somehow, that rumor was real. Welcome to the wonderfully glitchy world of item duplication in Pokémon Red and Blue.
The famous Pokémon Red and Blue item duplication trick is most commonly known as the MissingNo. glitch or Old Man glitch. It lets players increase the quantity of the item in the sixth slot of the Bag, usually turning one precious item into a stack that feels like it came from a Team Rocket warehouse. Rare Candies, Master Balls, Nuggets, vitamins, and valuable TMs are popular choices because, let’s be honest, nobody is doing this for extra Potions.
This guide explains how to duplicate items in Pokémon Red or Blue in four simple steps, why the glitch works, what items are best to duplicate, and what risks to know before you start surfing along Cinnabar Island like a tiny digital chaos wizard.
What Is the Pokémon Red and Blue Item Duplication Glitch?
The item duplication glitch is a programming quirk in the original Generation I Pokémon games. In simple terms, the game can be tricked into creating unusual wild encounters near Cinnabar Island after the Old Man catching tutorial in Viridian City. When the player encounters certain glitch Pokémon, including MissingNo., the quantity of the item in the sixth Bag slot increases dramatically.
Most players use this trick to duplicate Rare Candies or Master Balls. Rare Candies instantly level up a Pokémon, while Master Balls catch any wild Pokémon without fail. In normal gameplay, both are limited. The duplication glitch changes that limit from “carefully manage your resources” to “congratulations, you now own a suspiciously large candy factory.”
The key detail is the sixth item slot. Not the first. Not the fifth. Not the item you are emotionally attached to. The sixth slot is the one affected by the glitch, so arranging your Bag correctly is the most important part of the setup.
Before You Start: Important Warnings
Although the MissingNo. item duplication glitch is famous and widely used, it is still a glitch. That means it can cause odd behavior. The most common side effect is Hall of Fame data corruption, which can make your Hall of Fame records display strange graphics or nonsense entries. This usually does not destroy your main save file, but it can make your champion history look like it was edited by a confused Porygon.
Players should also avoid catching MissingNo. unless they understand the possible effects. Encountering MissingNo. is enough to duplicate the item. You do not need to catch it, defeat it, name it, invite it to dinner, or let it into your Pokémon Storage System.
If you are playing on original hardware, be extra careful with your save file. If you are using the Nintendo 3DS Virtual Console versions of Pokémon Red or Blue, the glitch still works, but it is still wise to save before attempting anything. If you are playing through an emulator, make a backup save state first. Glitches are fun; losing a beloved Charizard named “BLAZEBOI” is less fun.
How to Duplicate Items in Pokémon Red or Blue: 4 Steps
Step 1: Put the Item You Want to Duplicate in the Sixth Bag Slot
Open your Bag and move the item you want to duplicate into the sixth position. This is the most important setup step because the glitch affects the quantity of the sixth item stack.
For example, if you want to duplicate Rare Candies, arrange your Bag so Rare Candy is the sixth item listed. If you want more Master Balls, place Master Ball in the sixth slot. If you want more Nuggets to sell for money, put Nuggets there instead.
To rearrange items in Pokémon Red or Blue, use the SELECT button in the Bag menu. Select the item, move it to the sixth slot, and confirm the placement. Count carefully. The Bag in Generation I is not exactly a modern inventory system; it has the elegance of a filing cabinet during an earthquake.
Step 2: Talk to the Old Man in Viridian City
Next, go to Viridian City and find the Old Man who teaches players how to catch Pokémon. He is located near the path north of Viridian City. Speak to him and agree to watch his catching demonstration.
During this demonstration, the game temporarily changes player-related data while the Old Man performs the tutorial. This is part of what makes the glitch possible. After the demonstration ends, do not fight random Pokémon, do not enter unnecessary battles, and do not wander around like you forgot why you came. Your next destination is Cinnabar Island.
Step 3: Fly to Cinnabar Island and Surf Along the East Coast
After watching the Old Man tutorial, immediately Fly to Cinnabar Island. Once there, head to the island’s eastern coastline. Use Surf and move up and down along the narrow edge where the land touches the water.
This strip of tiles is famous because it can trigger strange wild Pokémon encounters after the Old Man glitch setup. Depending on your player name and game data, you may encounter MissingNo., ‘M, high-level Pokémon, or other unusual glitch-related encounters.
Stay on the eastern edge of Cinnabar Island and keep surfing vertically. Eventually, a wild encounter should appear. If the screen announces “Wild MissingNo. appeared,” you have found the celebrity glitch itself: part Pokémon, part programming hiccup, part 1990s playground mythology.
Step 4: Encounter MissingNo. and Check Your Sixth Item
Once MissingNo. appears, you do not need to catch it. You can run away from the battle. The item duplication effect happens from the encounter itself. After leaving the battle, open your Bag and check the sixth item slot.
The quantity should now be much higher than before. In many cases, the item count increases by 128, creating a stack that may display unusual symbols if the number exceeds the normal two-digit display. Do not panic if the quantity looks odd. That is normal for this glitch. Use or toss items carefully if you want the count to return to a more readable number.
That is the entire process: place the item sixth, watch the Old Man tutorial, Fly to Cinnabar Island, Surf along the coast, encounter MissingNo., and enjoy your duplicated item. Somewhere, a Poké Mart cashier just felt a disturbance in the economy.
Best Items to Duplicate in Pokémon Red and Blue
Not every item is worth duplicating. You technically can duplicate many stackable items, but some give you much better value than others. Here are the most useful options.
Rare Candy
Rare Candy is the classic choice. It instantly raises a Pokémon by one level, making it incredibly useful for completing the Pokédex, preparing for the Elite Four, or turning a low-level team member into a battle-ready monster without spending hours in tall grass.
However, there is one strategy note: leveling only with Rare Candies can skip some stat experience gains from battle. For casual play, this usually does not matter much. For players who care about maximizing stats, use Rare Candies thoughtfully rather than feeding your Pokémon like they are at an all-you-can-eat candy buffet.
Master Ball
The Master Ball is another favorite. Since the game normally gives you only one, duplicating it removes the pressure of choosing the “perfect” target. Want to catch Mewtwo without weakening it? Master Ball. Legendary birds being annoying? Master Ball. Random level 3 Pidgey giving you attitude? Technically also Master Ball, though Professor Oak may quietly judge you.
Nugget
Nuggets are great for making money. Since they sell for a high price, duplicating Nuggets can fund your Poké Ball purchases, healing items, vitamins, and general shopping needs. It is the closest thing Kanto has to printing money, minus the legal paperwork.
Vitamins
Items such as HP Up, Protein, Iron, Carbos, Calcium, and other stat-boosting vitamins can also be valuable. They help improve Pokémon stats and are expensive to buy, so duplicating them saves a lot of money.
Valuable TMs
Some TMs in Pokémon Red and Blue are limited. If you duplicate a useful TM, you can teach that move to multiple Pokémon instead of agonizing over who deserves it. This is especially helpful for powerful or rare moves that fit several team members.
Why Does the MissingNo. Glitch Duplicate Items?
The short explanation is that Pokémon Red and Blue store certain data in ways that can overlap under unusual conditions. The Old Man tutorial temporarily changes how the game handles the player’s name data. When you then surf along Cinnabar Island’s east coast, the game may use leftover or unexpected data to generate wild encounters.
MissingNo. stands for “Missing Number,” referring to an invalid or unused Pokémon index number. When the game processes this glitch Pokémon, it also affects the value connected to the sixth item quantity in your Bag. That is why the sixth item increases.
This is not a normal cheat code added by the developers. It is an unintended bug caused by how the original games handle memory, encounter data, and item quantities. In modern terms, it is a programming accident. In classic Pokémon terms, it is basically Kanto’s weirdest side quest.
Does the Glitch Work in Pokémon Yellow?
The classic Red and Blue method is most strongly associated with Pokémon Red and Pokémon Blue. Pokémon Yellow has differences that affect how MissingNo. and related glitches behave. Some item duplication methods exist in Generation I discussions, but the exact Old Man and Cinnabar setup is best known for Red and Blue. If your goal is the simple four-step item duplication method, Pokémon Red or Blue is the version you want.
Does the Glitch Work on the 3DS Virtual Console Versions?
Yes, the MissingNo. item duplication glitch is known to work in the Nintendo 3DS Virtual Console releases of Pokémon Red and Blue. These versions preserve many original game behaviors, including several famous glitches. That said, the same warnings still apply: save first, avoid unnecessary risk, and remember that glitch behavior is not the same as normal gameplay.
Common Mistakes That Stop the Glitch From Working
The Item Is Not in the Sixth Slot
This is the most common mistake. The item must be in the sixth Bag slot before you encounter MissingNo. If your Rare Candy is fifth or seventh, the glitch will not duplicate it. Count your items carefully before starting.
You Did Something After the Old Man Tutorial
After watching the Old Man catching demonstration, go directly to Cinnabar Island. Extra battles or certain actions can disrupt the setup. Think of the glitch as a soufflé: weirdly fragile, easy to ruin, and not something you should explain too loudly in a restaurant.
You Are Surfing in the Wrong Place
You need to Surf along the eastern edge of Cinnabar Island, where the coast meets the water. If you are surfing randomly in the ocean, you may only find ordinary water Pokémon. Stay close to the land edge and move up and down.
Your Player Name Affects Encounters
The wild encounters generated by the glitch can depend partly on your player name. Some names make MissingNo. appear more reliably than others. If you encounter unusual Pokémon but not MissingNo., the glitch may still be working; you may simply be seeing different results based on stored data.
Is It Safe to Duplicate Items?
For many players, duplicating items with MissingNo. works without damaging the main save file. The most famous side effect is corrupted Hall of Fame data. This means your record of Pokémon League victories may display scrambled graphics or strange entries after encountering MissingNo.
The safest approach is simple: save before trying the glitch, duplicate only what you need, run from MissingNo., and avoid catching or using glitch Pokémon unless you are deliberately experimenting. If your main goal is more Rare Candies or Master Balls, there is no reason to push the glitch further.
Helpful Tips for Using Duplicated Items Wisely
Duplicating items can make Pokémon Red and Blue easier, but it can also remove some of the challenge. If you give yourself unlimited Rare Candies before the second Gym, the adventure may feel less like a journey and more like a paperwork error at the Pokémon League.
A balanced approach is to use the glitch after you have already experienced most of the game naturally. For example, duplicate Rare Candies when preparing extra Pokémon for the Pokédex or duplicate Master Balls when catching roaming-style targets is not part of the game but legendary patience-testing certainly is. Use Nuggets if you want convenience without completely changing battle difficulty.
For collectors, the glitch is especially useful. Completing the Pokédex in Generation I can require a lot of training, trading, and item management. Extra Rare Candies can speed up evolutions, while duplicated TMs can help create more flexible teams.
Personal Experience: What It Feels Like to Use the Pokémon Red and Blue Item Duplication Glitch
The first time you successfully duplicate an item in Pokémon Red or Blue, it feels less like using a cheat and more like discovering a secret trapdoor in your childhood bedroom. The setup sounds ridiculous: talk to an old man, fly to Cinnabar Island, surf on a suspicious strip of coastline, and wait for a pixelated error creature to appear. If someone described it without context, you would assume they were making it up to win a playground argument.
But that is part of the charm. Pokémon Red and Blue are polished enough to feel magical, yet old enough to show their seams. The MissingNo. glitch sits right at that intersection. It is not just a trick for unlimited Rare Candies. It is a reminder that these games were built with tight memory limits, clever shortcuts, and programming decisions that sometimes produced accidental legends.
In practice, the most satisfying item to duplicate is usually Rare Candy. There is something deeply funny about watching a scarce item suddenly become abundant. One minute, you are carefully deciding whether your underleveled Dratini deserves a boost. The next, you are sitting on enough candy to make the Celadon Department Store nervous. It can turn Pokédex completion from a slow grind into a much friendlier project.
Master Balls are fun in a different way. Duplicating them removes the stress from legendary encounters. Instead of saving the Master Ball forever because “what if I need it later,” you can actually use it. That alone feels revolutionary. Many players finish entire RPGs with rare items untouched, waiting for a perfect moment that never arrives. The MissingNo. glitch politely kicks that habit into the ocean.
Still, the glitch is best enjoyed with a little restraint. If you duplicate everything immediately, you may flatten the game’s sense of progress. Pokémon Red and Blue are partly about small victories: earning money, managing items, training your team, and surviving caves with six fainting Pokémon and one overworked Pikachu. Unlimited resources can make those moments disappear.
A good middle ground is to use duplication as a postgame tool. Beat the Elite Four first, explore the world normally, then use the glitch to experiment. Build strange teams. Raise Pokémon you ignored. Teach rare TMs without regret. Catch Mewtwo with style. Sell Nuggets and buy whatever you want. At that point, the glitch becomes less of a shortcut and more of a sandbox mode.
The other memorable part is seeing MissingNo. itself. It looks strange, mysterious, and almost spooky in a harmless retro way. It does not feel like a normal wild Pokémon. It feels like you opened a door the game forgot to lock. For many longtime fans, that encounter became one of the most iconic moments in Pokémon history, not because it was intended, but because it was shared, repeated, whispered about, tested, and eventually understood.
That is why the item duplication glitch still matters. It is not only about getting more items. It is about the culture around early Pokémon: rumors, notebooks, link cables, schoolyard discoveries, and the thrill of realizing a game could contain secrets even the instruction manual did not mention. The glitch is messy, useful, risky, funny, and unforgettable. In other words, it is peak Generation I.
Conclusion
Duplicating items in Pokémon Red or Blue is one of the most famous glitches in video game history. By placing the desired item in the sixth Bag slot, watching the Old Man tutorial in Viridian City, flying to Cinnabar Island, and surfing along the east coast until MissingNo. appears, players can dramatically increase valuable items such as Rare Candies, Master Balls, Nuggets, vitamins, and TMs.
The glitch is simple, but it should be used carefully. Save your game first, avoid catching MissingNo. unless you know what you are doing, and remember that Hall of Fame data may become corrupted. Used wisely, the MissingNo. item duplication glitch can make Pokémon Red and Blue more flexible, more experimental, and honestly, a lot more hilarious.
