An implantable prosthesis is provided for repairing a fistula, such as an anal fistula. The prosthesis or fistula repair device may include a body with a shape configured for placement in the fistula. The prosthesis may also include an anchor or base that is located at one or both ends of the body to facilitate anchoring the prosthesis in position. The prosthesis may include one or more channels to create one or more pathways for drainage and/or irrigation of the fistula. The channel may have a relatively uniform dimension along its length or a tapered shape that increases along its length. The prosthesis may have an adjustable length for accommodating fistula tracts of varying lengths. The prosthesis may include elongated body segments that provide a wicking or capillary function to facilitate drainage of the fistula tract.