To assess the accuracy of detection of breast cancers by mammography and stereotactic fine-needle biopsy (SFNB) 2594 mammographically detected non-palpable lesions were sampled. On the basis of combined evaluation by mammography and cytology of these samples, 2005 (77.3%) of the cases were judged as benign lesions without need of surgery and only 1 of these turned out to be a cancer 14 months later. In 567 (21.9%) patients diagnostic and/or therapeutic surgery was done. Breast cancer was confirmed by histopathology in 429 (75.7%) of the patients operated on and a further 60(10.6%) had non-malignant pathological changes (eg, sclerosing adenosis, epitheliosis, fibroadenoma, or papilloma). Thus, surgery was justified in 86.3% (489) of the patients. In addition to the histopathologically verified cancers, another 22 (0.8%) breast cancers were diagnosed by mammography and cytology but these patients were not subjected to surgery for various reasons. A combination of mammography and SFNB offers a procedure of high sensitivity for early diagnosis of breast cancer.