The authors reviewed the CT findings of 31 cased of primary retroperitoneal tumors confirmed by operation(25 cases) or needle biopsy(6 cases) at the Chonnam University Hospital from J une, 1983 to August, 1988. The size, shape, location, margin of mass, effect on the surrounding structures, presence or absence of metastasis and the composition of th e tumor were analyzed to find the differential points between benign and malignant tumors and characteristic findings of each tumorsThe results were as follows; 1. The benign tumor showed smaller size than malignant one and well circumscribed round or 。void lesions,and no surrounding invasion or distant metastasis 25. Santos L A, Ginaldis, Wallace S: Computed tomography in liposarcoma, Can cer 47:46, 1981 26 천혜정， 임진우， 최재결， 차안호， 서원혁 : 후복막에 생긴 지방육종의 전산화단충촬영소견， 대한방사선의 학회지 23 : 247 , 1987 27. Waligore M P , Stemphens D H, Soule E H, Lipomatous tumors of the abdominal cavity; CT appearance and pathologic correlations, AJR 137:539, 1981 28. Friedmann A C, Hartman D S , Sherman ], Lautin E