Objective? To investigate the pathogenesis, diagnosis, and treatment of unilateral gluteal muscle contracture. Methods Between January 1990 and September 2009, 41 patients with unilateral gluteal muscle contracture were treated and the cl inical data were retrospectively analysed. Among them, 24 were male and 17 were female with an age range from 6 to 29 years (mean, 12 years). Thirty-nine patients had a definite history of repeat intragluteal injection. The locations were the left side in 9 cases and the right side in 32 cases. The main cl inical manifestations included lameness and abnormal gait. The medical examination showed pelvic obl ique and relative inequal ity of lower l imbs with a mean difference of 2.1 cm (range, 1.2-3.8 cm) in the distance form navel to malleolus medials. The X-ray films of pelvis showed outpouching trochanter of femur and pelvic obl ique. The CT scans showed no abnormal finding except pelvic obl ique and gluteal muscle contracture. The arc longitudinal incision was made into the posterolateral area nearby the greater trochanter and then lysis of the gluteal muscles was performed, followed by the skin traction of both legs and rehabil itation exercise. Results All incisions healed by first intention. Forty-one patients were followed up 1-20 years (mean, 5 years), and the signs of gluteal muscle contracture disappeared. After 1 year of operation, 34 patients had equal leg length, 5 patients had mild pelvic obl ique, and 2 patients had obvious pelvic obl ique. According to LIU Guohui et al. evaluation standard, the results were excellent in 33 cases, good in 6 cases, and poor in 2 cases with an excellent and good rate of 95.12% at 1 year after operation. Conclusion Unilateral gluteal muscle contracture leads to pelvic obl ique and inequal ity of lower l imbs, and it can be cured with 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 rehabil itation exercises.