We studied 12 patients (13 bones) with intraosseous lipoma to elucidate the clinical features of this disease. The patients ranged in age from 14 to 54 years. Eleven patients were men and 1 was a woman. The involved bones were the calcaneus in 6 patients (7 bones), humerus in 3, ischium in 2, and sacrum in 1. Three bones were in Milgram's stage I, 8 were in stage II, and 2 were in stage III. On plain radiographs, all bones showed a well-circumscribed radiolucent area. Nine bones showed calcification or ossification. Computed tomography or magnetic resonance imaging showed low density or high signal intensity, respectively, identical to the findings in normal adipose tissue. The tumor was curetted in 3 patients (3 bones), in whom local recurrence was not seen thereafter. In the remaining 9 patients (10 bones), we observed the natural course; in 1 of these patients, incisional biopsy was performed. During the follow-up period, only 1 patient showed slight enlargement of the lesion, while the findings in the others remained unchanged. Three patients had pain, which disappeared after the surgery or during the course of the observation. Partly because intraosseous lipoma tends to undergo spontaneous involution, and partly because diagnosis is easy from the radiological findings, surgery does not seem to be necessary in most patients.