Binding of Isaac: Rebirth Wiki
Binding of Isaac: Rebirth Wiki

Fistula is a boss that can appear:

The large Fistula has 60 HP, the medium forms have 15 HP, and the small forms have 8 HP.


  • Moves around the room slowly, bouncing off the walls.
  • When enough health is depleted, the one large Fistula breaks into four medium Fistulas.
    • Medium forms behave identically but move slightly faster and can bounce off other enemies.
  • Each of the four medium Fistulas breaks into two small Fistulas.
    • Small forms behave identically but move very fast.
  • Each of the smallest Fistulas spawns a Charger with 15 health points on defeat unless they are over a pit or other obstacle.

All stages of Fistula deal a whole heart of contact damage.

Champion Versions Needs to be unlocked[]

  • Dark Grey: 15% larger with 25% more HP (75). Spawns Boom Flies with 15 health points instead of Chargers. Each piece travels much slower and splits into three medium Fistulas as opposed to the original's four, similar to Teratoma.



  • Fistula appeared in the original The Binding of Isaac.
  • A fistula is an abnormal connection between organs, intestines, and other tissues.
  • Fistula’s splittings after taking enough damage is a reference to the game Asteroid, where asteroids would float diagonally and split after taking enough damage. This was confirmed by Edmund McMillen.
  • Fistula used to be a Caves/Catacombs boss in the original The Binding of Isaac, but as of Rebirth, it was a Cellar boss.
    • Added in Repentance It has been moved back into the Caves as of Repentance.
  • Teratoma is the posthumous version of Fistula.
  • Unlike the original The Binding of Isaac, Fistula doesn't bounce off of rocks.
  • Fistula was inspired by a boss of the same name in another Edmund McMillen game, C-Word.
  • Added in Afterbirth † Fistuloid is an enemy variant of this boss combined with what looks to be a Charger or Spitty.
  • Added in Afterbirth † The Matriarch is a boss added in Booster Pack #5 that is simultaneously based of a Fistuloid, Chub, and this boss. The Matriarch will also spawn small Fistulas throughout the battle.
  • Added in Repentance Mother will spawn a unique Fistula with a rotten appearance during one of her attacks.
    • A similar Looking Fistula can be encountered in the Corpse.
  • Added in Repentance Fistula is one of four bosses that can be spawned by It Lives, the other three being Chub, Polycephalus and Teratoma.

Bosses Boss Monstro.png
Chapter 1
Stage Basement icon.pngStage Cellar icon.pngStage Burning Basement icon.png
GeminiStevenBlighted OvumDingleThe Duke of FliesFamineGurglingsThe HauntLarry Jr.MonstroPinWidowThe FallenThe Headless Horseman
DangleLittle HornRag ManTurdlings
Baby Plum
Chapter 1.5
Stage Downpour icon.pngStage Dross icon.png
Lil BlubWormwoodThe RainmakerMin-MinClogColostomiaTurdlet
Chapter 2
Stage Caves icon.pngStage Catacombs icon.pngStage Flooded Caves icon.png
FistulaChubC.H.A.D.Carrion QueenDark OneGurdyGurdy Jr.The HollowThe HuskMega FattyMega MawPeepPestilencePolycephalusThe WretchedThe FallenThe Headless Horseman
The ForsakenThe FrailThe Stain
Big HornRag Mega
Chapter 2.5
Stage Mines icon.pngStage Ashpit icon.png
Reap CreepTuff TwinsHornfelGreat GideonSingeThe ShellThe Pile
Chapter 3
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The AdversaryThe BloatThe CageThe GateMonstro IIGishLokiMask of InfamyWarThe FallenThe Headless HorsemanMom
Sisters Vis
Reap CreepThe Pile
Chapter 3.5
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Chapter 4
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BlastocystThe BloatConquestDaddy Long LegsTriachnidDeathLokiiMama GurdyMr. FredScolexTeratomaThe FallenThe Headless HorsemanMom's HeartIt Lives
Sisters VisThe Matriarch
Stage Corpse icon.png
ChimeraThe ScourgeRotgutMother
Chapter 5
Stage Sheol icon.pngStage Cathedral icon.png
Chapter 6
Stage Dark Room icon.pngStage Chest icon.png
???The LambMega Satan
The Void
Stage The Void icon.png
Stage Home icon.png
DogmaThe BeastUltra DeathUltra FamineUltra PestilenceUltra War
Greed Mode
Ultra Greed
Ultra Greed
Ultra Greedier
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