Hip subluxation and dislocation are common orthopaedic problems in children with cerebral palsy. Selective posterior rhizotomy(SPR) is a neurologic procedure aimed in reducing spasticity. Several recent studies have indicated a decrease in spasticity and functional improvement after SPR, and also decrease the tendency toward hip subluxation in children with cerebral palsy. This is a retrospective study to examine whether SPR halts hip subluxation. Between May 1994 and July 1996, 22 children below age of 5 underwent SPR. Twenty children were spastic diplegic types and 2 were mixed type and quadriplegic type respectively. Approximately 50-80% of L2-Sl level dorsal roots was cut, and 13 children had 50% of both Ll roots cut. Migration percentage score (MP) was used to determine progression of hip subluxation during the follow up period (12 36 mos.; Average 15 mos.). Of the total 44 hips in 22 patients, 45.5% (20 hips) improved, 34% (15 hips) remained unchanged, and 20.5% (9 hips) were worsened after SPR. Radiographic stability was achieved in 79.5%. Ll root cut rate (Ll SPR) was 55.5% for improved hips, 67% for unchanged hips, and 50% for worsened hips. Two patients had undergone orthopaedic procedure for progressive hip migration. Most patients experienced postoperative hip stability after SPR, but 20.5% were worsened and 2 patients had orthopaedic procedure. Also it is unlikely that Ll root involvement prevents progression of hip migration.