Hamstring spasticity causes varying degrees of difficulty in sitting with knee extension, short stride walking, and also can cause croutch gait due to flexion contracture of the knee. The spacticity has been managed by either proximal or distal hamstring release, and there are some controversies in managing the spasticity even now. In order to determine the efficacy of the proximal hamstring release, we evaluated the 109 cases in 57 spastic cerebral palsy patients who had been treated with proximal hamstring release in Seoul National University Childrens Hospital from August 1985 to December 1991. There are 34 male patients and 23 female patients. The mean age at the time of surgery was 12 years and 8 months (range, 3 years and months-14 years and 10 months). The mean follow-up period was 2 years and 7 months (range, 1 year-5 years and 8 months). There were 32 cases of paraplegia, 18 diplegia, 5 quadriplegia, and 2 hemiplegia. Postoperative results were assessed by comparing the changes of the measured angles, such as, straight leg raising (SLR), popliteal angle, and knee flexion contracture or hyperextension. And the functional results were assessed by the postoperative changes of following: sitting posture with knee extension, lumbar lordosis in standing, stride length, and ambulation status. Results are as following; 1. SLR was improved from 48.3° to 78.1° in average postoperatively, popliteal angle was improved from 50.2° to 15.2° in average, and knee flexion contracture was converted from 1.3° of hyperextension of the knee to 3.6° of hyperextension. 2. Sitting posture with knee extension was improved in 54 cases(94.7%), but lumbar lordosis was increased from 20° to 41.8° in average postoperatively. Although preoperative accurate measurement of the stride is difficult due to subjective description, short or very short strides were converted to adequate stride in 11 cases, short stride in 29 cases and very short stride in 17 cases. 3. Overall functional results were excellent in 18 cases, good in 25 cases fair in 10 cases and poor in 4 cases. In conclusion, proximal hamstring release is a reasonable approach for the management of hamstring spasticity if stride length and sitting posture are the main problem without severe contracture of the knee.