The data on 98 new patients with osteoblastoma were studied. The clinical features of pain, scoliosis, and neurologic deficit were largely consistent with those in previous reports. Osteoblastoma is usually a lytic lesion originating in the medulla of bones with matrix ossification and mild surrounding sclerosis. Osteoblastoma of the spine demonstrated better tumor delineation in the vertebrae, and a bony rim on the soft-tissue side was seen less frequently than previously observed. Osteoblastoma of the talus frequently appears as a blister on the surface of the bone and is accompanied by osteoporosis. In the hands and feet, the radiographic appearance is often very similar to that of aneurysmal bone cyst and giant cell tumor. In the skull it strongly resembles a button sequestrum of bone. The origin and extent of the tumor, the presence of matrix mineralization, and tumor delineation depicted as a thin bony shell are often better appreciated on computed tomographic (CT) scans. In addition, CT can demonstrate both edema and atrophy of the surrounding soft tissues. At magnetic resonance (MR) imaging, osteoblastoma demonstrates signal intensities similar to those of other bone neoplasms. In addition to the advantages offered by CT, MR imaging can help differentiate tumor tissue from accompanying edema.