In a prospective, randomized, double-blind study the effects on infection rates of a 1-day and a 3-day course of cefuroxime versus placebo were studied in patients undergoing peripheral vascular surgery. During a 30-month study period 211 patients were randomized to one of three treatment groups: Group I Placebo; Group II cefuroxime 1 day; Group III cefuroxime 3 days. Cefuroxime was administered intravenously (1.5 g every 8 hours) and the first dose was given 1 hour before surgery. Wound infection rates in the three treatment groups were: Group I 16.7%; Group II 3.8% (p less than 0.05 vs placebo); Group III 4.3% (p less than 0.05 vs placebo). One graft infection occurred in 110 patients at risk (0.9%) and this occurred in the placebo group. No allergic reactions or other side effects were noted in any of the treatment groups. No cefuroxime-resistant bacteria were found in Group II or III. In conclusion, prophylactic administration of cefuroxime during 1 day significantly reduced the incidence of infectious complications following peripheral vascular surgery. Extension of the prophylaxis beyond the day of surgery offered no additional effect. The study supports the use of short-term prophylactic antibiotics in vascular surgery.