The following are known Action Replay Codes for Final Fantasy: Mystic Quest on Super Nintendo Entertainment System (SNES).

• 198 Cures after one is used
  00C0194E
• Infinite Cure Potions
  00C019BE
• Use Cure get Cure
  00C019FE
• Use a Cure Potion when you have 2 characters, and it will give you 48,000 HP
  00C019FF
• Cure Potions are Bombs
  00C025F0
• Each Cure Potion restores life to maximum
  00C02900
• Cool attacks
  02850B3C
• Infinite Magic Points
  0285AB3C
• Infinite Bombs (Only in battle)
  02904FA5
• Bombs take off a lot more than seen
  02905FA4
• Bombs take off a lot
  02905FA6
• Infinite Ninja Stars
  0290BBA5
• Protagonist always has around 2,000 HP
  7E101508
• Protagonist always has 99 Bombs (Regardless of type)
  7E103063
• Second Character always has around 2,000 HP
  7E109508
• Second Character always has 99 of their numbered weapons (Typically Throwing Stars or Arrows)
  7E10B063
• Every Cure Potion restores health to maximum
  00A04044
  15C049D5
• Wierd attacks
  00B0704D
  15E0A919
• Cool attacks
  00B0704D
  15E0A949