p6 participants in the Veterans Administration Cooperative Studies Program investigating antibiotic prophylaxis in colorectal operations, 693 consecutive patients (1978-1981) from three hospitals were studied. This report concerns 20% of these patients who presented with either perforation, obstruction, or hemorrhage necessitating emergent surgical intervention on unprepared bowel. The 30-day, in-hospital mortality of the 138 patients undergoing emergency operations was 28%. Elective colorectal procedures during the same period had a six per cent mortality rate. There is a striking difference in the cause of death in prepared patients and those needing emergent surgery. Death in prepared patients was usually of a vascular etiology, while septic-related mortality was present in only one per cent. On the other hand, despite massive doses of antibiotics, fecal diversion, surgical drainage and lavage, abdominal sepsis was documented in 20% and septic related mortality was present in 17% of patients undergoing emergency operations. Early, elective treatment and prevention of obstruction and perforation will improve our results in colorectal disease.