Acute diverticulitis following surgery is a severe condition reported previously only after heart surgery. Four cases of diverticulitis in the early postoperative period are presented, three of them after non-cardiac procedures (tracheostomy, inguinal hernia repair and laminectomy). Advanced age, administration of morphine, treatment with steroids, postoperative constipation and intestinal mucosal ischaemia are discussed as possible aetiological factors leading to diverticular perforation. Although the diagnosis is often difficult, early treatment offers the best chance of survival.