We evaluated under controlled conditions the efficacy of topical and systemic antibiotics, alone and in combination, in the prevention of wound infection and measured serum and tissue antibiotic levels in the wound and distant tissue after administration of antibiotics topically, systemically, and in combination. Adult Sprague-Dawley rats were contaminated on the dorsal paravertebral muscles with a preset standardized inoculum of Staphylococcus aureus, Escherichia coli, and Bacteroides fragilis. A second-generation cephalosporin was used; systemic administration was given intramuscularly and topically in powder form. Wound infection was confirmed by the recovery of the organism by culture. Prophylactic antibiotics were effective in preventing wound infection in all groups. Topical antibiotic and a combination (topical/systemic) antibiotic were significantly more effective than was systemic antibiotic alone in preventing wound infection. Adequate levels of antibiotic were achieved in serum and tissue with both topical and systemic antibiotics. Wound tissue concentration of antibiotic was significantly higher when topical antibiotic was used.