PURPOSE: Breast cancer risk assessment tools have been developed in western countries as a result of large scaled epidemiological studies. These tools have been used as a rationale for breast cancer screening and to determine the selection criteria of NSABP P-1 and P-2. The aim of this study was to develop a breast cancer risk assessment tool for Korean women, which would be helpful for screening and preventing breast cancer. METHODS: The breast cancer risk model was used published by Sue Kyung Park in 2003. The report was a case- control study of 1687 breast cancer patients and 1155 normal populations in 3 hospitals from 1996 to 2000. The risk factors used in this model were age, family history of the first and second relatives, body mass index, age at the first delivery, breast-feeding and a special test on the breasts. A computer program was developed using the Borland Delphi on a personal computer using a windows 98 operating system. The program consisted of three parts; an input window of the risk factors, a calculation part of the relative risks, an output window of the results. RESULTS: The program was a 308K byte sized single executable file. In the initial window, a simple explanation of the program and a reference of the risk model were displayed. The age, height and weight were entered as continuous variables in the input window. The family history of the first and second relatives, the age at the first delivery, breast-feeding and a special test on the breasts were selected by the radio buttons. In the output window, the relative risks were calculated according to each risk factor. The overall relative risk was calculated in a given age group and the overall age group. CONCLUSION: In this study, a computer program for a breast cancer risk assessment was developed using the relative risk model of breast cancer. This program was found to be useful for making an individual breast cancer risk assessment of Korean women.