Colonic perforation is the second most common complication of colonic neoplasms and is associated with an elevated morbidity and mortality. We undertook a two-centre retrospective analysis of 378 colonic neoplasms seen from 1978 to 1985. Thirty-six patients (9.5%) presented with a perforated colonic carcinoma. Two-thirds had a past history suggesting colonic disease while in the remaining one-third, the perforation was the first manifestation of the disease. Resection was carried out initially in 33 cases (21 Hartmann's procedure, 9 primary anastomosis, 2 mucous fistula and 1 abdominoperineal excision). Two patients had a proximal colostomy only and 1 an exploratory laparotomy only because of disseminated disease. Postoperative mortality was 14% (five cases). Actuarial survival rate was 52% at 1 year and 40% at 2 years. Eleven patients are still alive after a mean follow-up of 43 months.