Distal bowel evacuation was studied by cinedefecography in 85 women with obstinate constipation, tenesmus, and incomplete evacuation in whom a diagnosis of internal rectal intussusception was clinically suspect. Sixty-five patients showed radiographic evidence of intussusception--mostly of the distal rectum, without rectosacral separation. Patients with distal intussusception who did not respond to nonoperative measures were treated by Delorme's transrectal excision with excellent results. Internal rectal intussusception is a real and demonstrable entity which may be symptomatically disabling and whose documentation may be integral to effective and anatomically specific treatment. The syndromes of perineal descent, solitary rectal ulcer, levator syndrome and so-called recurrent hemorrhoids may be diagnostic intermediaries in the evolution of internal rectal intussusception.