In wounds of the hand and forearm treated within 4 h of injury, prophylactic clindamycin, in a dose of 150 mg 6-hourly for 5 days, did not reduce the infection rate. In wounds treated after 4 h the infection rate was reduced, but not significantly so. There was a significant reduction in the infection rate comparing all wounds treated within 4 h with those treated after 4 h. Early treatment of wounds is more important than prophylactic antibiotics, although these may have a part to play where late treatment is unavoidable.