During the past five years my co-workers and I have been making a concerted effort to control the occasional sporadic operating room infection occurring in a case of otherwise clean operation. About 90 per cent of the infections have been caused by Staphylococcus aureus, usually of the hemolytic type. Occasionally there has been a mild infection with Staphylococcus albus and rarely a severe infection with Streptococcus haemolyticus. Beginning with the cleansing of the skin of the patient, the operating room technic was checked throughout. This survey covered the skin of the operative field, the hands of the operating team, the linen used for draping, sponges, autoclaves, sterile water tanks, hot water sterilizers, oil sterilizers, brushes, instruments, gloves, plain and chromic catgut, needles, silk, scalpels and solutions and powder for the hands and gloves. Cultures of these were uniformly found to be sterile. Freshly laundered doctors', nurses' and orderlies' uniforms and