The purposes of this study were to determine the rate of infection associated with elective outpatient operations on an extremity, performed in a double-occupancy operating room (one operating room designed to accommodate two separate operating teams), and to determine which factors influenced this rate. We evaluated the records of 2458 consecutive patients who had had such a procedure, performed by one of nine surgeons during a two and one-half-year period, and in whom the operative wound had been classified as clean (without a drain) or clean-contaminated (with a drain). The information regarding the factors associated with the operation and the operating-room environment was recorded for each patient at the time of the operation. Each wound was inspected periodically in the attending surgeon's office for at least thirty days postoperatively. Using definitions established by the Centers for Disease Control, the attending surgeon determined the presence of infection primarily by judging whether there was purulent drainage or whether erythema or swelling at the operative site was beyond that expected from the procedure.Of the 2458 patients, thirty-seven (1.5 per cent; 95 per cent confidence interval, 1.1 to 2.1 per cent) had infection of the operative wound. Only eight patients (0.3 per cent) had deep infection, with seven of the infections necessitating a reoperation. Infection developed in thirty of the 2311 clean wounds, a rate of 1.3 per cent (95 per cent confidence interval, 0.9 to 1.8 per cent), and in seven of the 147 clean-contaminated wounds, a rate of 4.8 per cent (95 per cent confidence interval, 2.3 to 9.5 per cent) (p = 0.001). No cross-contamination occurred between patients who had infection. The rate of infection was not related to the number of patients who were operated on in the same room at the same time. Logistic regression analysis, used to account for confounding factors, demonstrated a significant association between the classification of the wound (use of a drain) and a higher rate of infection (p = 0.006) as well as between the instillation of a topical steroid solution and a lower rate of infection (p = 0.04). It also demonstrated a significant difference, with respect to the rate of infection, among individual surgeons (p = 0.02).