Fortress of the Yuan-Ti is an adventure module for the 3.5 edition of the Dungeons & Dragons fantasy role-playing game.

Fortress of the Yuan-Ti is an adventure in which evil yuan-ti conspire to destroy a kingdom using dark rituals and the bones of a long-dead king.

The player characters must storm the yuan-ti fortress and take the bones from the cultists before they complete their rituals and unleash a far greater menace upon the world.

Fortress of the Yuan-Ti was written by Ari Marmell, and was published in September 2007.

Cover art was by Steve Prescott, with interior art by Dave Griffith.