A survey of prophylactic antibiotic-prescribing habits among chiefs of surgical services of the Veterans Administration yielded a 99% response. These responses have been compared with guidelines set by an expert committee on antimicrobial use for the VA central office. Assuming that 100% concordance with the standards of the committee is a desired state, the average hospital is approximately one third away from this goal (average score, 62.4%). The majority of errors were those of overuse rather than underuse. The size of the service and the existence of a university affiliation had no influence on the results. Feedback to the chiefs of service regarding the use of antibiotics was informal and tended to be carried out on rounds rather than as a result of formal audits. Most senior surgeons indicated that they would be willing to be influenced by audit guidelines. (JAMA241:717-718, 1979)