A double-blind, controlled trial was performed to assess the effect of a short intraoperative course of Cefoxitin®, a new broad spectrum cephamycin antibiotic, on the incidence of septic complications following elective colonic and rectal surgery. In addition to a two-day preoperative bowel preparation, patients entered in the study received a short course of either Cefoxitin (three 2g intravenous bolus doses at two-hour intervals, the first before skin incision) or a matching placebo. Thirty-two patients received Cefoxitin and 33 patients received the placebo. Postoperative abdominal wound infections developed in one (3%) of the Cefoxitin-treated patients and nine (27%) of the placebo-treated patients. This difference is statistically significant (p=0.01). Septic complications remote from the abdominal wound, e.g. intra-abdominal abscesses, occurred in both Cefoxitin-treated and placebo-treated patients, but numbers were too small for meaningful analysis. The study shows that even a very short peroperative course of Cefoxitin is highly effective in reducing postoperative abdominal wound infections after elective colorectal surgery.