The 35 patients who have suffered from myositis ossificans were investigated for 112 years. They were posttraumatic patients. They trauma was divided into 3 group ; spinal cord injury, direct injury (fracture) and mixed type involving both. We evaluated the age distribution, the frequency of myositis ossificans, prediliection site , bilaterality and relation between predilection site and bilaterality to the type of trauma. The results are as follows ; 1. The age distribution was highest in 4th decades (12 among 35 patients). 2. In regard to distribution of 35 patients, spinal cord injury were most common (15 cases, 43 %), the fracture nextly common (14, 40%) and then mixed type (6, 17%). 3. Among 51 cases of myositis ossificans, the frequency was highest in spinal cord injury(25 cases, 49%), next was fracture(14, 27%). 4. The predilection site of myositis ossificans were thigh(18 cases, 35%), hip(17, 33%) and buttock(6, 12%). 5. In correlation between predilection site of myo itis ossificans and level of spinal cord injury , hip is the most frequent site in thoracic injury. 6. The bilaterality of myositis ossificans is 39%(20 among 51 lesions).