Thirty adults (17 male and 13 female patients) with spastic disorders were treated by hamstring releases of 46 extremities. The diagnoses were stroke, traumatic brain injury, spinal cord injury, multiple sclerosis, and anoxia. The mean age at surgery was 38.6 years. Three extremities had partial release of the hamstring tendons behind the knee; the remaining 43 extremities had a complete release. The average position of the knee was 61.4 degrees of flexion preoperatively and 6 degrees postoperatively. The follow-up period averaged 21.3 months. Preoperatively, 87% of patients were nonambulatory. Following hamstring release 43% became ambulatory and 17% had gained the ability to transfer. Complications included two stroke patients with severe peripheral vascular disease; one developed a large nonhealing sore of the ankle and the other developed gangrene of the foot. Both patients required amputation. Three other patients developed recurrent flexion contractures that have since been rereleased with good results.