In 310 patients, divided into groups receiving penicillin and streptomycin, cephalothin, or no antibiotics, culture specimens were taken at four stages of triage, and each patient was followed and observed for infection. A correlation was made between retrieval of bacteria after injury and incidence of infection. In control patients the incidence of infection was 13.9 per cent while in the group receiving penicillin and streptomycin it was 9.7 per cent, the difference not being statistically significant. The group of patients receiving cephalothin had a significantly lower infection rate of 2.3 per cent.