Introduction: Intraosseous hemangioma is an uncommon benign vascular tumor, usually developing in adults of 2nd to 4th decades rather than infants like other hemangioma, and mainly involves the craniofacial bones and vertebrae. Intraosseous hemangioma generally show poor response to medical therapy, and surgical resection, radiation therapy, embolization or laminectomy±spinal fusion of vertebral lesion are recommended as treatment for symptomatic cases. We report three cases of intraosseous hemangioma developed in the forearm of children. Case Report: First patient was a 12-years-old girl, who had extensive lymphangioma involving Rt. forearm and right hand diagnosed at birth. She received surgical resection of lymphangioma for 6 times which could not remove lymphangioma completely. She visited our hospital because of newly developed intraossous hemangoioma in the midshaft of radius and deep muscular part of forearm at age of 12. Second patient was a 12-years-old boy who presented with intermittent pain of the right forearm without trauma since a month ago. MRI detected intramuscular hemangioma with intraosseous hemangioma involving ulnar and radius. The third patient was a 14-years-old boy from China, who presented with left arm swelling since one year ago, and had been treated with regular intravenous bleomycin in China. In MRI, aggressive hemangioma infiltrating deep muscular structure and radius bone was detected. All three cases of intraosseous hemangioma of forearm with intramuscular hemangioma involving surrounding muscles. The initial CBC, chemistry and coagulation profile were normal. First and second patients were treated with oral propranolol therapy (2mg/kg/day #3) for 6 months, but did not show improvement. Follow up MRI in the third patient did not show change in hemangioma after bleomycin therapy in China. We are planning to treat with interferone alfa 2b for the next step with basic study in future.