PURPOSE: To evaluate the efficacy of Flexible intramedullary pin fixation in pediatric forearm diaphyseal fractures. MATERIALS AND METHODS: In this retrospective study, we reviewed 15 cases of forearm diaphyseal fractures operated using flexible intra-medullary nail fixation technique between January 2000 and December 2004. Of these 15 children, there were 11 boys and 4 girls with an average age of 11.6 years (range, 7~15 years). The implants were introduced in the distal radius and proximal ulna in all patients. An average duration of fixation was 5.3 months in the radius, 4.7 months in the ulna. After operation, all patient were applied with a long arm cast and the duration of immobilization was 5.2 weeks (range, 4~6 weeks) on average. RESULTS: All fractures in this series healed with normal range of supination (average 80.0) and pronation (average, 71.6 degrees). Average operation time including anesthesia was 123 minutes and hospital stay was 5.4 days. Time to union was 8.4 weeks on average. Range of motion and functional results were satisfactory in all cases. There were one case of incomplete ulnar nerve injury and two cases of refracture which were treated conservatively without any permanent complication. CONCLUSION: Flexible intramedullary pin fixation technique is a good method in case of unstable displaced fracture and difficult or failed closed treatment.