To evaluate the usefulness of aspoxicillin (ASPC) in the field of plastic and reconstructive surgery, we examined its transfer to the skin. 1. After intravenous drip infusion of ASPC for 1 hour at a dose of 2 g in 13 adults and at 1 g in 2 children, the mean serum ASPC concentration 1 hour after termination of the infusion was 70.46 +/- 28.05 micrograms/ml. The mean concentration in the skin tissue 1 hour after infusion in 15 patients was 32.45 +/- 18.47 micrograms/g. The rate of transfer to the skin 1 hour after infusion in the 15 patients was 52.9 +/- 29.7%. 2. The ASPC concentrations in skin tissues and the rates of its transfer to the skin did not differ significantly between 5 patients with facial surgery and 10 with surgery in the trunk or limbs. 3. To prevent postoperative infections, ASPC was intravenously drip infused twice daily for 2 approximately 3 days after operation at a dose of 2 g in adults and 1 g in children. No postoperative infection occurred in any patient, suggesting the effectiveness of this drug. In addition, no side effects or abnormalities in clinical examination values were observed.