To establish the effective mass screening projects for the breast cancer, our study group cosponsered by the Welfare Ministry was organized by 11 regional groups. From 1968 to 1986, 643, 513 women at the initial screening and 719, 189 women at the subsequent screening were examined by physical examination. Out of them, abnormalities were present in 24, 864 women (3.9%) and 23,880 (3.3%), respectively. A detection of cancer was made in 833 women (detection rate 1.3%) and 428 women (0.6%), respectively. As the examinees increased from year to year, the subsequent examinees were over the initial ones. It was suggested that most of examinees had been fixed year by year and the detection rate of initial screening had been higher than that of the subsequent one. Then more initial examinees are expected to be increased. Women 30 to 59 years of age were mostly screened, but women aged 60 or more should be increased. Of women with abnormal physical findings, women over 90% took the second examination. But more effective, economical and safer screening instruments are expected to be developed and be used at the first examination.