The purpose of the present study was to determine whether unilaterally operated total hip arthroplasty (THA) patients were superior to bilaterally operated THA patients with respect to aerobic endurance capacity, muscle strength and gait patterns 3-5 years after surgery, and to what extent medial femoral head offset (FO) influenced hip abductor strength. 10 unilaterally operated THA patients with normal FO (UNO), 10 bilaterally operated THA patients with normal FO (BNO) and 10 bilaterally operated THA patients with abnormal offset (BDO) participated in the study. Improved muscle strength in the healthy leg of the UNO did not result in differences compared to the BNO and the BDO in work efficiency, gait patterns or maximal oxygen consumption (VO2max ) A reduced FO in the BDO did not result in lower hip abduction strength compared to the BNO. However, a correlation between reduced FO and low abduction strength was found in the BDO (r=0.866, p=0.001). Future focus should be on the quality of rehabilitation.