The purpose of this study was to analyze the outcome in patients with acute obstruction of the left colon for cancer and treated by intraoperative decompression, on-table lavage, resection, and primary anastomosis. Between March 1992 and May 1998, 50 patients with acute obstruction of the left colon for cancer underwent surgery. Of these, 39 patients (25 men and 14 women; mean age, 65 years; range, 23-89) were treated with intraoperative decompression, on-table lavage, resection, and primary anastomosis. Six patients (15%) had fecal localized peritonitis. Left colectomies were performed in 16 patients (32%), partial colectomies in 19 patients (38%), and anterior resections in 4 patients (8%). The primary anastomosis was intraperitoneal in 29 patients (74%) and below the peritoneal reflection of the rectum in 10 (26%). The postoperative course was uneventful in 30 of the 39 cases. One patient (3%) died (within 30 days from surgery) from septic shock and multiple organ failure syndrome. Anastomotic leakage was observed in 2 patients (6%). An intra-abdominal abscess occurred in one case (3%). Other common complications included wound infections in 3 patients (8%). This experience suggests that intraoperative decompression, on-table lavage, resection, and primary anastomosis can be performed safely in selected patients with acute obstruction of the left colon for cancer than in those with an anastomosis in the nondiverted colon. Anastomosis below the peritoneal reflection is also not a contraindication.