A controlled prospective study of 2165 outpatients undergoing skin surgery was performed to evaluate the utility and the effects of several antibiotic schedules for prophylaxis of wound infections. The patients were divided into four groups. Twenty-three of the 541 group A patients, given no antibiotics, had wound infections. Eight of the 542 group B patients, given systemic antibiotics from immediately after surgery until the third day, had wound infections. Four of the 540 group C patients, treated only with local sterile antibiotic powder sprinkled into the wound during surgery, had wound infections develop, and only one infection occurred in the 542 group D patients given systemic antibiotics from 2 days before surgery until the second day after surgery. This last schedule was the best for prophylaxis of wound infections in contamination-prone regions. Local antibiotic administration is a simple method for prevention of infections in routine skin surgery.