Although most patients with jejunoileal diverticulum are asymptomatic, a large, small-bowel diverticulum can be associated with midgut volvulus in an adult. We present a rare case of midgut volvulus that was associated with a large, small-bowel diverticulum in a 77-year-old woman presenting with chronic recurrent abdominal pain. The CT showed the characteristic whirl sign of twisted mesentery, the small bowel loops along the superior mesenteric artery and a large sac-like small-bowel diverticulum. A small bowel series also demonstrated a corkscrew appearance of proximal jejunum, a finding suggestive of midgut volvulus, and a large jejunal diverticulum. During the laparotomy, the small bowel was seen twisted counterclockwise 270 degree. The mesenteric root was very shortened. A 4 cm sized diverticulum was seen on the mesenteric border of jejunum, on the portion about 40 cm distal from the Treitz ligament.