Fat containing masses, except mediastinal lipomatosis, of the thorax are uncommon. In spite of uncommonoccurences, as CT can detect not only the fat content but also the presence and character of the non-fattycomponent of the mass, accurate preoperative diagnosis can usually be made in most cases of fat containingmediastinal masses. Authors report 6 cases of fat containing mediastinal masses, that were diagnosedpreoperatively by CT scan, comprising 2 cases of limpoma(combined with plexiform neurofibroma in a case), 1liposarcoma, 1 thymolipoma, and 2 cases of omental hernia through Morgagni foramen.