Objectives: The aim of this study is to evaluate the effect of selective dorsal rhizotomy (SDR) on functional abilities in a well-defined group of ambulatory children with spastic diplegia. Methods: Nine children were selected for SDR (mean age 65 months, range 43-82 months). Gross motor function was measured with the Gross Motor Function Measure (GMFM-88). Self-care was assessed with the Pediatric Evaluation of Disability Inventory (PEDI) and gait pattern was measured with the Edinburgh Visual Gait Score (EGS). There were nine single-case research designs with a 12-month follow-up after surgery. Results: After 12 months the mean improvement in the total GMFM-88 scores was 8.8%. On an individual level, all patients improved significantly in comparison with baseline. Functional skills and care-giver assistance measured with the PEDI showed significant improvement. Improvement in gait was also found; in particular, better initial contact and heel-lift resulted in an increased EGS. Conclusion: In this well-defined group of ambulatory children SDR had a small but significant positive effect on gross motor function, self-care and gait pattern. © Springer-Verlag 2005.