Of 361 patients who survived curative left colonic or sphincter-saving rectal resection for cancer, 44 developed significant postoperative intra-abdominal sepsis and 317 did not. The two groups were well matched for age, sex, site of tumour, Dukes stage, tumour differentiation and timing of operation. There was no significant difference in the 5-year overall actuarial survival rate (P = 0.25) or in the 5-year disease-free survival rate (P = 0.23). Stepwise regression analysis of prognostic variables including age, sex, site of tumour, Dukes stage, tumour differentiation, timing of operation, grade of surgeon and postoperative intra-abdominal sepsis identified Dukes stage, age at operation and tumour differentiation as predictors of survival. These results suggest that postoperative intra-abdominal sepsis is not a prognostic factor for long-term survival in colorectal cancer as has been previously reported.