PURPOSE: The purpose of this study was to evaluate the efficacy of annual breast screening, which includes a mammography and a clinical physical examination. METHODS: From April 1995 to March 2000, we performed 51,170 annual clinical examinations and mammographies on 26,354 women, who wanted to undergo breast screening, at the breast center. Ninety-five breast cancers were detected during screening, and of these, only 76 breast cancers were operated on. The result were compared with 650 symptomatic breast cancers from the outpatient department (OPD). RESULTS: Of the 51,170 cases screened, the recall rate for further examination was 9.9% (n=5,066), and the biopsy rate was 2.1% (n=1,096). Ninety-five breast cancers were detected; a detection rate of 0.19%. Fourteen breast cancers were detected after more than 2 screening rounds. On the analysis of the medical audit data based on the screening mammographies, the positive predictive value, confirmed when a biopsy from a surgical consultation was recommended (PPV), was 8.6%. Further, 41 cases involving tumors found at stage 0 or I (54%). There were 25 cases of axillary lymph node metastasis (32.9%). These results were compatible with the ideal rates for medical audits, except for PPV and axillary lymph node metastases. The pathologic stages of the screened group were: 0, 22.4%; I, 31.6%; II, 40.8%; III, 5.2%, whereas those of the OPD group were 0, 3.4%; I, 27.4%; II, 52.8%; III, 15.5%, and IV, 0.8%. Early breast cancers were detected more frequently through screening than by the OPD (P<0.05). Breast conservation surgery was carried out on 32.9% (25 cases) from the screened group, but only 12.8% (83 cases) from the OPD group (P<0.05). CONCLUSION: Our breast cancer screening was properly performed. Further, these findings indicate that breast cancer screening using a clinical examination and a mammography is very effective in the early detection of breast cancer.