Sixty-one non-traumatic perforations in free peritoneum are reported. The principal aetiology is diverticulitis (35 cases) followed by cancer (22 cases). 18 derivations were carried out, 34 colectomies without anastomosis, 5 ideal colectomies and 4 diverticulectomies. Total mortality was 19.7-14% for diverticulitis, 22.2% for perforations at the cancer site, 50% from diastasic perforations. Stress is laid on the need to treat colic perforation by colectomy without anastomosis, confining derivation openeum. Sixty-one cases.