Myositis ossificans progressiva is rare hereditable disorder characterized progressive heterotopic bone formation in connective tissue and muscles in association with congenial skeletal anomalies. We report the plain radiologic and MR findings of myositis ossificans progressiva in two children. One case showed discrete ossification in the right buttock, neck, and both chest walls on plain radiographs, while the other showed diffuse swelling of the left posterior neck, back, and buttock muscles, which was demonstrated on MR images. Both cases showed associated anomalies in the hands and feet.