Early detection of breast cancer and reduced mortality in women with this disease is today attributed to the widespread use of mammography. High-quality performance is essential in every step of breast cancer screening programs in order to avoid unnecessary anxiety and surgery in the women concerned. This report presents the radiologic aspects of screening cancers. A total of 8370 asymptomatic women aged between 50-69 years were screened with 2-view mammography, of which only 70 (0.84%) were selected for surgery after a thorough work-up. Cancers were verified histologically in 61 women and 9 showed non-malignant histology, giving a cancer detection rate of 7.3 cancers per thousand screened asymptomatic woman. The benign/malignant ratio in the operated cases is thus approximately 1:7. The cancers detected showed all existing types of mammographic features where 77% (47 cases) showed rather typical findings, such as spiculated densities both with and without microcalcifications and with microcalcifications only. The remaining 23% (14 cases) showed parenchymal distortions, asymmetric and well-defined densities, both with and without calcifications. Our results indicate that surgery can be minimized without impairing the breast cancer detection rate. Radiologists in screening programs should be aware that a large proportion of non-palpable breast cancers present in rather unconventional forms. This point is important in order to maintain a high cancer detection rate and thereby justify the widespread use of mammography as a screening tool for breast cancer in asymptomatic women.