In a prospective trial conducted at five medical centres, 136 patients aged 18 to 75, undergoing elective gastro-intestinal surgery were randomized to receive a single dose of cefotaxime, 1 g preoperatively, or cefoxitin, 2 g preoperatively followed by 2 g every 6 h for no more than 24 h. Overall infection rates with both regimens were approximately 10%. There were no significant differences in the infection rates between subgroups. Thus, a single preoperative 1 g dose of cefotaxime is as efficacious as, but considerably more cost-effective than, multiple 2 g doses of perioperative cefoxitin in the prevention of infection following elective gastrointestinal tract surgery.