In this paper I have reviewed the current literature on the genetic mutations found in association with breast cancer. More emphasis has been given to BRCA1 because of the excitement generated with the cloning of this breast cancer susceptibility gene. A number of somatic mutations have been described (loss of heterozygosity, overexpression, and other mutations) in breast cancers. While strides have been made in unraveling the genetic basis of hereditary breast cancer (10 to 15 percent of all breast cancers), the genetic causes of most sporadic breast cancer (which comprise 85 to 90 percent) have yet to be discovered but they are likely the result of a step wise progression of cumulative genetic events, similar to those seen in colon cancer.