Body position during assessment of muscle strength is one of the variables that must be controlled to ensure the validity and reliability of isokinetic dynamometer [15,16]. Assessment of hip abductor and adductors muscles strength is usually tested with the subject in sidelying position [10,17-19]. Widler et al. [20] assessed the isometric hip abductor muscle strength from supine, side-lying and standing positions. They found that the side-lying body position offers the most valid and reliable assessment of unilateral hip abductor strength. However, Cahalan et al. [7] suggested that standing position is the most functional position for the assessment of hip abductor muscles strength, Claiborne et al. [21] established a high test-retest reliability measurement of isokinetic hip abductors and adductors torque from standing position. Therefore, the purpose of this investigation was to examine the effect of the standing and side-lying position on concentric peak torque of hip abductor and adductor muscles.