This study was conducted to estimate incidence rate of female breast cancer in a defined area of Chungchongbuk-do in Korea. The presumptive breast cancer cases were selected from two different sources, i.e., medical utilization database of the National Health Insurance Corporation and the database from the National Cancer Registry. Medical students visited each hospital where the presumptive cases had been treated as a breast cancer patient, and made a dictation of medical record of each patient based on the claims stored in the Insurance Corporation from January to December 1995. The diagnoses in the claims included one of the following diagnostic codes; ICD-9 174-175(malignant neoplasms of the breast), 233(carcinoma in situ of the breast and genito-urinary system)or ICD-10 C50(malignant neoplasms of the breast), D05(carcinoma in situ of the breast and genito-urinary system). Each case has been confirmed as having a breast cancer by a breast surgeon through a medical record review. Age-standardized incidence rate of female breast cancer to the Korean population was estimated to be 10.5(95%confidence interval : 8.1-12.9)per 100,000 persons in 1995. Age-standardized rate to the world population was 9.8 per 100,000 persons, and the truncated rate for ages 35-64 was 27.2 per 100,000 persons. Validity of these estimates is discussing in comparison with previous methods of incidence estimation in Korea.