Rotatable sphincterotome is inserted into a flexible endoscope for orienting the distal cutting wire tip of the rotatable sphincterotome in a twelve o'clock position, where the distal cutting wire tip cuts the sphincter muscle of a patient. It has a housing and a flexible tubular member protruding from the housing. A slidable member is slidably connected on the housing for moving the distal cutting wire tip in a longitudinal direction to cut the sphincter muscle.