The familial aggregation of prostate cancer and breast cancer has been observed for almost half a century and about 85% of the inherited breast cancer can be linked to germ-line mutations of BRCA1 (breast cancer 1, early onset) and BRCA2. In this review, we are mainly focusing on the contribution of BRCA1/2 sequence variations to prostate cancer risk and disease progression. We will discuss the biological functions of BRCA1/2 and BRCA1/2-related signaling pathways in prostate cancer biology. The majority of studies supporting the link between BRCA1/2 mutations and prostate cancer are from populations with a high frequency of mutations, such as Ashkenazi Jewish, Icelandic, and U.K. population. BRCA1 can directly interact with the androgen receptor (AR) and Janus kinase (JAK), and can differentially regulate insulin-like growth factor 1 receptor (IGF-IR) expression in an AR-dependent manner. BRCA2 homeostasis in prostate cancer cells has been found to be critical in determining cell fates during prostate cancer progression. This review may be helpful for medical professionals and prostate cancer patients when discussing prostate cancer risks, treatment and prognosis.