Selective posterior lumbar rhizotomy has recently become an alternative method for relieving spasticity in patients with spastic cerebral palsy. This procedure involves the selective sectioning of the lumbosacral posterior nerve rootlets. Because the whole nerve root is not cut, tactile and proprioceptive sensation remain intact. The present study measured the changes that occurred in 29 patients with spastic cerebral palsy 2 days before surgery and from 4 to 14 months after surgery. Each patient was used as his or her own control. In addition to the clinical evaluation of function, gait was analyzed on appropriate patients with a simple digital camera and microcomputer. The results indicated positive gains after rhizotomy. These gains were, however, dependent on the patients' abilities before surgery. The most significant improvement occurred in thigh and knee ranges of movement. This somewhat controversial new method of treating spasticity shows promise in improving the quality of life of patients with spastic cerebral palsy and in facilitating their treatment.