This rare case of arteriovenous hemangioma occurred in the right thigh of a 17-year-old Japanese female with leg pain induced by running. Ultrasonic examination showed a hyperechoic mass with a central hypoechoic area in the distal portion of the semimembranous muscle adjacent to the ipsilateral popliteal artery. CT and MRI depicted a heterogeneous mass in the same location. In gross terms, the mass consisted of nests of small vessels and fatty tissue within the muscular bundle. Histologic evidence of vessels mimicking veins adjacent to vessels resembling arteries lacking an intimal elastic fiber layer lead to a diagnosis of arteriovenous hemangioma. Correlation of ultrasonic and pathologic findings suggested that the central hypoechoic area represented hemangioma itself, while the surrounding hyperechoic lesion indicated fatty infiltration of the muscle.