This study aimed to determine the frequency of the 6174delT mutation in the BRCA2 gene in women with breast cancer (BC) and women who tested negative for breast cancer but who were in a group at high risk for breast cancer. In this study were 10 families with hereditary breast cancer. It included 40 women, 25 women with breast cancer and 15 who were not identified with breast cancer. the authors used PCR amplification of DNA 6174delT, and Fermentas and BbrPI restriction enzymes to identify the 6174delT mutation in BRCA2. The results of this study are as follows: the authors did not identify the 6174delT mutation of BRCA2 in 25 women with a family history of breast cancer and 15 women with a high risk of breast cancer. Therefore, the 6174delT mutation of BRCA2 is not a common mutation among women in Hai Duong province with a family history of breast cancer.