A previously well 7-week-old boy was found unresponsive and cyanotic in his cot in the morning. Resuscitative attempts achieved only partial response with subsequent terminal cardiac arrest occurring later in the day. At autopsy a large intestinal volvulus was found associated with disseminated Clostridium perfringens sepsis. In addition, a duplication cyst of the terminal ileum was present. Although rare, right-sided colonic volvulus may be a cause of unexpected death in infancy. While predisposing factors to volvulus may include intestinal duplication cysts, the anatomic relation of the duplication to the volvulus must be carefully determined before a causal relation can be accepted; the cyst in this case was most likely incidental to the terminal event.