A case of haemoperitoneum arising from an omental haematoma is described. Histology suggests that this resulted from an omental torsion. The omentum, however, was not torted at the time of laparotomy. Furthermore, there was a history of similar episodes of pain over the previous eighteen months. This suggests that spontaneous derotation of an omental torsion may occur, and may be an unusual cause of recurrent abdominal pain.