OBJECTIVES: To assess the compliance with antibiotic prophylaxis practices and identify the factors associated with practice variations in total hip replacement (THR) surgery. METHODS: We carried out a retrospective survey of medical records in the orthopedic surgery department in a 2,200-bed university hospital. A sample of 416 patients undergoing THR from January 1999 to December 2000 was drawn. Practice conformity was evaluated based on French guidelines for good clinical practice concerning antibiotic prophylaxis in orthopedic surgery. Five major criteria were used: antibiotic prophylaxis use; choice of molecule; dosage at first injection; time between first injection and incision; total duration. A multilevel hierarchical logistic regression analysis was performed using global conformity as the dependant variable. RESULTS: Among the 386 medical records analyzed, antibiotic prophylaxis was used in 366 (95%) interventions. The choice of molecule was consistent with the reference for 258 (70%) patients. Among patients receiving a recommended molecule, dosage and timing of first injection were consistent respectively for 98% (290 / 296) and 80% (236 / 296). The total duration of treatment was restricted to 48 hours for 360 of 366 (98 %) patients. Global conformity, defined as the combination of the five major criteria, accounted for 52 % (201/386) of patients undergoing THR surgery. After multivariate analysis, a statistically significant association was found between the global conformity and the prescribers (p=0.03). The interventions during 1999 (AOR 0.61; 95% CI 0.40-0.92) were associated with a risk of non-conformity. Adherence to guidelines for antibiotic prophylaxis practice was not associated with prescriber's characteristics. CONCLUSIONS: Although French guidelines were recently published, the appropriateness of antibiotic prophylaxis in THR surgery could still be enhanced especially in terms of the rational choice of a molecule and timing of the first injection.