This study was designed to assess the medical and surgical treatment of colonoscopic perforations.A retrospective review of colonoscopic perforations from 1970 to 1999 was performed.In 30 years, 34,620 colonoscopies resulted in 31 (0.09 percent) perforations. Eighteen (58 percent) resulted from therapeutic colonoscopies, whereas 13 (42 percent) occurred after diagnostic colonoscopies. Sixteen perforations (52 percent) were identified during the procedure, 13 (42 percent) within 24 hours, and two (6 percent) within 48 hours. Twenty patients (65 percent) underwent surgical therapy, and 11 (35 percent) were treated medically with intestinal rest and intravenous antibiotics. In the medically treated group, one patient required rehospitalization for percutaneous drainage of an intra-abdominal abscess, and one patient died after requesting no further treatment because of an underlying terminal medical condition. Three patients failed medical treatment and required surgical intervention. One underwent repair with proximal diversion, whereas the remaining two received a colorrhaphy without resection or diversion. In the surgical treatment group, nine patients received colorrhaphy without diversion, seven underwent resection with primary anastomosis, and four had resection with diversion.Selected patients with colonoscopic perforation may be safely treated nonoperatively. Surgical treatment is reserved for patients with a large perforation or diffuse peritonitis.