Despite the widespread success of total hip arthroplasties for treatment of arthritis of the hip, the procedure continues to be targeted for cost control. Our objective was to compare the total in-hospital cost of primary total hip arthroplasties in high-volume and low-volume hospitals. Data concerning the patient-level in-hospital costs of 940 consecutive primary total hip arthroplasties were extracted from the cost accounting system of three Canadian hospitals. Mean in-hospital costs for patients having total hip arthroplasties in a high-volume institution (> or = 300 total hip arthroplasties/year) compared with two low-volume Canadian institutions (