Authors retrospectively analyzed ultrasonographic findings of 61 cases of breast lesions which were provenpathologically at Dae Rim St. Mary's Hospital from May 19987 to Feb. 1990 The results were as follows: 1. Of all61 cases, there were 27 fibroadenomas, 13 fibrocystic diseases, 11 carcinomas, 8 abscessses, 1 sclerosingadenosis, and 1 intraductal papilloma. 2. Findings suggesting benignancy were smooth contour, round or oval shape,homogeneously echolucent internal echo, echogenic boundary echo, and posterior enhancement. In the cases ofabscess, the findings were rather irregular contour, strong posterior enhancement, and dirty, inhomogeneousinternal echo. While irregular and lobulated shape, inhomogeneous and mixed internal echo and pectoral muscle invasion were suggested for malignancy. 3. The sensitivity was 98% and the specificity 58% in benign mass excluding abscesses, 63% and 98% in abscesses, and 55% and 98% in carcinomas. In conclusion, ultarsonography isone of the excellent imaging modality for detecting breast lesions larger than 5mm in size, but unfortunately someof the malignant tumors simulate benignancy, thus we considered fine needle aspirartion biopsy and adjuntive imaging modalities such as film mammography most be followed for better detection of breast cancer.