PURPOSE: Although the standard treatment of diaphyseal forearm fractures in children is conservative treatment with closed reduction and cast immobilization, unstable or irreducible fractures are usually needed by surgical intervention. The aim of this article is to determine the efficacy of the percutaneous transphyseal intramedullary K-wires fixation for the forearm diaphyseal fractures in children. MATERIALS AND METHODS: In this retrospective study, we reviewed 18 cases of forearm diaphyseal fractures in children, which were treated with percutaneous transphyseal intramedullary nailing using K-wires from January 2001 to December 2004. We analyzed the period for radiologic bone union and the complications until the last follow-up. RESULTS: The average period of follow-up was 15 months with mean age of 7.8 years. The average time to bone union was 6.2 weeks and nonunion, malunion, radio-ulnar synostosis and refracture were not found, just 2 local pin site infections were seen but healed by conservative treatment. Postoperative scar was small and the complications until the last follow-up were not found. CONCLUSION: In the operative treatment of the forearm diaphyseal fractures in children, we think percutaneous transphyseal intramedullary K-wire fixation is one of the effective methods because of the minimal invasiveness, simplicity and easiness in removal.