We have evaluated 4 cases of congenital proximal radioulnar synostosis corrected by proximal derotational osteotomy. Surgery was only indicated in cases with more than 60 degrees of pronation. Mean age at the time of surgery was 7 years and 4 months and mean postoperative follow-up time was 8 years. Forearm position after surgery ranged from 15 to 0 degrees of pronation. Aesthetic and functional improvement was achieved in all cases. No complications were observed the Surgical technique is reviewed.