Mediastinal lipomatosis induced by steroid is an unusual byproduct of such theraphy and has been reported after prolonged and large doses of steroid therapy. The radiologic findings of mediastinal lipomatosis in simple chest film are nonspecific, but with the advent of CT scan, differentiation the fatty lesion from other mediastinal deseases can be made easily. Recently we expended steroid induced huge mediastinal lipomatosis and report the case with review including radiologic findings