Adult midgut malrotation is very rare. The presentation in adults is mostly subtle; the diagnosis is often made on imaging. A 32-year-old man presented with a 3-day history of an irreducible painful mass protruding per rectum, followed by abdominal pain and obstipation. The patient was febrile and toxic, with marked signs of peritonitis and complete full-thickness irreducible rectal prolapse. Abdominal radiographs showed multiple air-fluid levels. A diagnosis of irreducible rectal prolapse with intestinal obstruction was made. Laparotomy revealed complete small bowel gangrene, abnormal rotation of the small bowel 180° around the mesenteric root, hypermobile duodenojejunalflexture and ileocaecal junction and an abnormally mobile caecal lying in the central abdomen. Abnormal mobility of the sigmoid colon with a large mesocolon, and a large irreducible rectosigmoid intussusception, was also noted. Our patient is probably the first case in literature, which may prompt awareness of simultaneously-occurring disorders of fixation, and preventive steps.