The higher costs associated with teaching hospitals have received some attention in the literature. The objective of the current study was to determine the increase in resource consumption associated with resident education in knee arthroplasty surgery. Seventy-four patients who underwent primary total knee arthroplasty in the same hospital were studied (50 private practice and 24 teaching practice). Time in the operating room and medical severity of illness were noted. Hospital charges were used as a measure of resource consumption. In addition, length of stay and in-hospital consultations and complications were observed. Kruskall-Wallis, chi square, and stepwise multiple regression analysis were performed. The mean age of the patients was 68 years. Patients who underwent surgery at the teaching service had higher charges ($30,311 +/- $3,325 versus $23,116 +/- $3,341) and longer times in the operating room (190 +/- 19 minutes versus 145 +/- 29 minutes). These patients also had a trend toward more associated comorbid medical conditions (0.71 versus 0.42). Stepwise multiple regression analysis showed that teaching was the most important predictor of charges and operating room time. The results show a 22% increase in perioperative resource consumption for patients who underwent surgery at a teaching service. The measured increase in cost is significantly lower than what has been reported in other series (82%). At the teaching institution, the anesthesia and orthopaedic surgery residents work together on all cases and perform a significant percent of the procedures under direct supervision. The increased resource consumption observed in a teaching service is most likely attributable to the hands-on approach taken to train residents.