Aims: The purpose of this study was to compare the hip abductor strength in patients undergoing total hip replacement via anterolateral (Müller) or posterolateral (Gibson) approach. Methods: Biomechanical studies were performed prospectively on a group of 80 patients who underwent hip arthroplasty via the anterolateral (48 cases) or posterolateral approach (32 cases). There were 61 females and 19 males with an average age of 57 years (range 37 – 78 years). The isometric abductor strength was measured with the kinetic communicator device preoperatively and 6, 12 and 24 weeks postoperatively. Results: Hip abductor strength improved postoperatively in both groups. The posterolateral surgical approach was associated with statistically significant higher abductor strength values. Conclusions: Posterolateral approach significantly increases the isometric abductor strength in relation to the anterolateral approach.