The bacteriological flora of the foot and shoe was studied concurrently in 200 volunteers without foot injuries, and 80 patients with puncture wounds of the foot. Seven of 28 child patients developed clinical infections, three with Pseudomonas aeruginosa. Eleven of 52 adult patients also developed infections. No patients developed infection if oral antibiotics were given within the first 24 h after injury (P < 0.05). Oral antibiotic prophylaxis is recommended for puncture wounds of the foot.