Objective To investigate the pathogenesis, diagnosis, and treatment of the gluteal muscle contracture associated with an unequal leg length caused by the pelvis obliquity (GMC-PO).Methods The retrospective analysis was made on the clinical features and the follow-up results in 132 patients who had been admitted from January 1990 to December 2004 for GMC-PO. Among them, 73 weremale and 59 were female with a range in age from 5 to 26 years (average, 11 yr). All the patients were characterized by unsymmetrical contracture of the gluteal muscles, including unilateral and bilateral contracture. Of the patients, 89 had a clear limping and 78 had a clearly-unequal leg length. The X-ray examination revealed pelvis obliquity in 97 cases and an increased angle of the femur neck in 11 cases. The arc longitudinal incision was made into the posterolateral area nearby the greater trochanter and then lysis of thegluteal muscles was performed, combined with the skin traction of both legs andexercise training. Results Of the 132 patients withunequal gluteal muscle contracture before operation, 13 had a relative length difference of 0.5-1.5 cm between the 2 legs, 1 had a difference of 3.0 cm,and the remaining 118 patients had an equal leg length. Excellent and good resultswere achieved in 118 and 13 patients, respectively after the surgical release of the gluteal muscle contracture by the arc longitudinal incision into the posterolateral area nearby the greater trochanter,combined with postoperative skin traction and functional exercises. Only 1 patient had a poor result. The follow-up for 3 months to 14 years showed that thecure rate was as high as 99.2%.Conclusion The gluteal musclecontracture associated with an unequal leg length caused by the pelvis obliquity is a result of the unequal gluteal muscle contracture between the 2 hips and it can be cured with a comprehensive therapeutic method including the surgical release of the gluteal muscle contracture by the arc longitudinal incision into the posterolateralarea nearby the greater trochanter, and postoperative skin traction as well as the functional exercise.