Breast cancer is a major public health problem. 1 woman in 8 will have breast cancer develop during her lifetime in America. As in the United States, long-term increases in the incidence of breast cancer are being observed worldwide. The high incidence of breast cancer in the female population is provide the rationale for screening. The principal purpose of screening for breast cancer is to reduce mortality from the disease through early diagnosis and treatment. It is demonstrate that mortality from breast cancer can be reduced as much as 30% in a screened population. Thus the authors tried screening for breast cancer by mammography with education in breast self examination and classified mammographic parenchymal pattern of the breast in the National Medical Center. The results obtained were summarized briefly as follows:1) Between 1995-5 and 1995-7, 329 women over aged 35 in National Medical Center were invited for screening by mammography with education in breast self examination and mammographic parenchymal pattern of the breast. 2) 294(89.3 percentage) women in 329 were attended for screening and mammographic parenchymal pattern of the breast. 3) A group of 16 women(4.9 percentage) was called for further assessment. 4) 5 women(1.7 percentage) had suspicious lesions and proceeded to surgical biopsy; 4 lesions proved fibrocystic disease and 1 lesion proved fat necrosis and dystrophic calcification. 5) The mammographic parenchymal pattern of the breast showed the number of women according to classification: 20%, 23%, 50%, 7% for N1, P1, P2, DY type, respectively. 6) The malignant lesion was not detect. The results are not statistically significant. But periodic mammography screening of asymptomatic women shows that a satisfactory cancer detection can be achievable. Follow-up of women over aged 35 in the National Medical Center is continuing.