How long to administer antibiotics after lung surgery is controversial. We investigated the feasibility of short-duration cefmetazole sodium administration as antibiotic prophylaxis after lung cancer surgery. A total of 40 patients were randomized into either a short-duration prophylaxis group (n=20) that was given 4 g of cefmetazole sodium for 2 days or a long-duration patients group (n=20) that was given 14 g of cefmetazole sodium for 7 days. Daily changes in body temperature, WBC, and plasma CRP concentration were determined for 9 days after surgery. The data were compared statistically between the 2 groups. Postoperative infection occurred in 20% of patients in the short-duration group and in 30% of patients in the long-duration group. The mean hospital stay after surgery was 15.5 days in the short-duration group and 18.6 days in the long-duration group. All variables did not differ significantly between the 2 groups. Our results indicate that short-duration antibiotic administration is an effective prophylactic treatment after surgery for lung cancer.