This study was conducted in a nonteaching community hospital to characterize the use of prophylactic antibiotics in patients undergoing total joint replacements by orthopedic surgeons in private practice. Of the 101 patients studied, 43 were started on antibiotics too early, 32 were left on the drugs for too long a period, and 33 received subsequent oral antibiotics without identifiable reason. Seventy-nine (78.2 percent) received 8 g/d of a first- or second-generation cephalosporin for prophylaxis. None of the patients received cefazolin 1 g q8h.