Objective To assess the medium- and long-term effectiveness of selective posterior rhizotomy (SPR) for spastic cerebral palsy. Methods A retrospective analysis was made on 27 patients with spastic cerebral palsy undergoing SPR between January 1997 and January 2008, whose data were complete with more than 5 years follow-up. There were 14 males and 13 females with an average age of 10.1 years (range, 4-19 years). All patients had simple spastic cerebral palsy, including 17 cases of bilateral spastic palsy and 10 cases of unilateral spastic palsy. The muscle strength, muscle tone, ambulatory function, the sharp foot and crossing-feet, knee jerk, ankle clonus, and Babinski’s sign were evaluated before and after operation. Results All the patients were followed up 5-16 years (mean, 9.6 years). No obvious limitation of lumbar flexion, extension and lateral flexion, spondylolisthesis, kyphosis, and other deformities occurred. At last follow-up, the muscle strength of hip extensors, hip flexors, and knee extensors were significantly increased when compared with preoperative ones (P lt; 0.05); but no significant difference was found in the muscle strength of hip abductors, hip adductors, knee flexors, plantar extensors, and plantar flexors (P gt; 0.05). Abnormal increased muscle tone of hip flexors, hip adductors, knee flexors, and plantar flexors was declined in different degrees in all patients, showing significant differences when compared with preoperative ones (P lt; 0.05); but no significant difference was found in hip extensors, hip abductors, knee extensors, and plantar extensors (P gt; 0.05). At last follow-up, the status of toe steps and crossing-feet disappeared without recurrence for a long time. Sthenic knee jerk was eliminated, but there were several patients also keeping the active knee jerk, showing significant difference when compared with preoperative ones (Z= — 7.404, P=0.000). The results of Babinski’s sign were negative in 31 sides and positive in 13 sides, showing significant difference when compared with preoperative ones (Z= — 6.897, P=0.000). No sharp foot or crossing-feet was observed. And ambulation ability was significantly improved after operation (Z= — 4.111, P=0.000). Conclusion SPR is very effective in decreasing the muscle tone and improving the motor function without recurrence in long-term.