An instrument for removing body tissue from a fistulous tract (1) is provided, including a cutting tool (10) having a blade (12) and a guide rod (30) to be guided through the fistulous tract (1). The cutting tool (10) has a tubular embodiment and it is slideable onto the guide rod (30). The cutting tool (10) has a rear guiding portion (16) for displaceably guiding the cutting tool (10) on the guide rod (30) and a front cutting portion (11), at a front end of which the blade (12) is formed, and the internal diameter (15) thereof is greater than the external diameter (34) of the guide rod (30) in order to form a receptacle cavity (14) for receiving severed body tissue (5).
