This study was undertaken by the University of Calgary Sport Medicine Centre, Physical Therapy Section. Financial support for the study was provided by a grant from the BE Schurr Memorial fund and the Canadian Physiotherapy Association (Calgary District). Information on the relative strengths of the muscles that internally and externally rotate the hip is scant. The present study used a Cybex(R) 340 isokinetic dynamometer to investigate hip rotation strength in 60 normal subjects. Subjects performed maximum internal and external hip rotation movements in each of three different testing positions. Results showed that hip rotation torques were significantly dependent on testing position (p < 0.05). Highest torques were obtained using a "seated" position, while a supine position with the knee flexed produced stronger torques than a supine position with the knee extended. Within each test position, internal rotation torques exceeded external rotation torques in all but one situation (p < 0.05). These findings contradicted previous reports that external rotation was the stronger of the two movements. Overall, the results provided valuable normative data on the relative strength proportions of the hip rotation musculature. J Orthop Sports Phys Ther 1992;16(1):43-50.