Background: Congenital radio-ulnar synostosis is rare condition, characterized by limited pronation and supination. It is typically diagnosed in school-aged children. The forearm is mostly fixed in a hyperpronated position. Transverse derotational osteotomy at the site of synostosis is the intervention we propose. Patients and methods: This is a retrospective study including 7 cases of congenital radio-ulnar synostosis followed and treated at the pediatric orthopedic department of the children's Hospital of Rabat between January 2006 to February 2017. Results: The average age is about 32.5 months with a male predominance. Bilateral involvement presents 57.7% of cases. According to the Cleary and Omer classification, 42.8% of cases are classified as type IV, and 57.1% of cases are classified as type III. The average degree of preoperative fixed rotation of the forearm is 66° (from 0° to 85°). Only one patient presents a poly-malformative syndrome. Ten forearms underwent surgery, with transverse derotational osteotomy at the site of synostosis, without any postoperative complications.