Intestinal volvulus in patients with Crohn's disease is rare and we could find only one report of sigmoid volvulus with active Crohn's colitis. We have seen a 54-year-old woman with long-standing Crohn's disease who developed large-bowel obstruction. After eventual detorsion of the sigmoid volvulus, we found that her ileum was involved with active Crohn's disease and that her colonic mucosa was free of mucosal lesions. In this case, we suspect that the reactivation of the ileal Crohn's disease as well as other features commonly associated with Crohn's disease contributed to the development of sigmoid volvulus by causing fixation, torsion, and dilatation of distal bowel.