O'Riordan, C., J. L. Adler, H. H. Banks, and M. Finland (Channing Laboratory, Boston City Hospital, Boston, Mass. 02118). Wound infections on an orthopedic service. A prospective study. Am J Epidemiol 95: 442–450, 1972.—A nosocomial infection rate of 11.8% was found in a prospective study of 279 consecutively admitted orthopedic patients over a period of 3½ months in 1970. One-half of the infections occurred in wounds, and all but one were in “clean” cases. Staphylococcus aureus was isolated from 35% of all infections. The isolates from infected wounds and from nasal and pharyngeal cultures of the surgical and nursing staff were of many different phage types. Advanced age and indwelling Foley catheters were the only significant factors related to the acquisition of wound infections, but a large proportion of the infected patients had undergone emergency surgery or repair of hip fractures. Breaks in isolation technique, overcrowding and lack of isolation facilities and of adequate ventilation were postulated as contributing factors.