Over a 9-month period from September of 1991 to May of 1992, 339 patients were included in a randomized, double-blind, placebo-controlled study using azithromycin as the prophylactic agent to determine whether it effects a clinically meaningful reduction in postoperative surgical infections in plastic surgery. Azithromycin was given as prophylaxis in 171 patients and placebo in 168 patients. The study medication was a single oral dose taken at 8 P.M. the day before surgery. The patients were followed up for a minimum of 4 weeks after surgery. The patients who received wound infection prophylaxis had 5.1 percent infections compared with 20.5 percent in the placebo group (p = 0.00009). Eighty percent of all wound infections were first seen after discharge, explaining why plastic surgeons might overlook their infectious complications. There was a significant reduction in postoperative complications (p = 0.04) and in the additional use of antibiotics postoperatively (p = 0.007) in the prophylaxis group. Subgroup analysis showed a significant reduction in surgical infections in breast surgery (p < 0.05) and reconstructive surgery with flaps (p < 0.05). No effect of the prophylactic regime was demonstrated in patients undergoing secondary surgery for cleft lip and palate disease.