After an uneventful hysterectomy for fibroids carried out in a woman of 48 years of age peritonitis developed on the 5th post-operative day. It was due to necrosing sigmoiditis which occurred in spite of normal bowel action having been resumed on the 3rd post-operative day. This is a rare but usually very severe post-operative complication. Immediate operation saved the patient but she had to have two further operative procedures.