The lipomatous of the mediastinum are fairly uncommon tumors. Since 1971, two patients with proven mediastinal lipoma and one primary liposarcoma of the mediastinum have been treated at the Seoul National University Hospital. This report reviews our experience with the review of literature. Case 1.: A 3 year old body revealed a huge round homogenous mass density in the posterior mediastinum in routine chest X-ray. The tumor mass, lipoma, was successfully removed and postoperative course was uneventful. Cases 2.: An asymptomatic 24 year old male was operated on with the preoperative diagnosis of mediastinal lipoma. His preoperative chest X-ray and CT films showed a huge anterior to middle mediastinal tumor, right, with fat density. There is no postoperative problem after successful removal of the tumor mass. Case 3. : A 24 year old female was hospitalized with the complaints of cough and chest pain. A mediastinal mass was removed, which proved to be a liposarcoma on pathologic examination. About one year later, she was found to have recurrent liposarcoma in the right chest area at the OPD follow-up. She was lost to follow-up since then. [KTCS 1983;3:375-380]