PURPOSE: To evaluate the clinical significance of the screening mammography in the detection of the breast diseases, especially breast carcinoma. MATERIALS AND METHODS: We analyzed 1,800 cases of mammography retrospectively. The mammography was done as a part of routine check in Health Counselling Center, Korea University Medical Center, during 9 months from November 1993 to July 1994. The age range was from 23 years to 76 years, mean 49.8 years, and the largest age group was 6th decade(31.4%). According to the mammographic findings, we divided the subjects into three groups; normal group, abnormal group in need of follow up study, abnormal group requiring biopsy. RESULT: On mammography, the normal group consisted of 1,534 cases(85%), and the abnormal group consisted of 266 cases(15%). The abnormal findings were benign-looking calcification(n=140), fibroadeno ma (n=29), fibrocystic changes (n=27), cyst(n=23), malignant lesion(n=15), lipoma(n=7), and others. In four of 15 cases, which were suspected to be malignant on mammograms, breast carcinoma was confirmed pathologically. In four cases of breast carcinoma, one was under 40 and the other 3 were over 50 years of age. All of the breast cancers were under 3cm in size, and the mammographic findings of breast cancer included spiculated margin(n=3), parenchymal disortion(n=3), malignant calcification(n=2) and enlarged axillary node (n=l). CONCLUSION: Screening mammogram is helpful for early detection of non-palpable breast cancer, especially for women over 50 years of age.