Idiopathic fecal incontinence is a clinical entity described mostly in the colorectal surgical literature and seldom encountered by the physiatrist. Evidence exists suggesting neuropathic injury to the external anal sphincter. Several reports have linked this syndrome to the descending perineum syndrome. A final answer to this diagnostic puzzle is yet to be found. This article presents a case of probable "idiopathic" fecal incontinence presenting during an evaluation for low back pain. Full evaluation yielded a denervating lesion of unknown etiology to the pudendal nerve. The patient was managed with a bowel program without success. Because physiatrists often find themselves managing cases of neurogenic bowel or bladder, it is important for the physiatrist to have a thorough understanding of idiopathic fecal incontinence. A discussion of the differential diagnosis and management of fecal incontinence is included.