Breast cancer is the most common cancer in Iran. In the recent years an upward trend has been observed in the Iranian population. Early detection by molecular approaches may reduce breast cancer morbidity and mortality. We provided consultation to 3,782 women diagnosed with early onset breast cancer during the past 15 years (1999-2014). To establish a data set for BRCA gene alterations of the Iranian families at risk, two hundred and fifty four women who met our criteria were analyzed. A total number of 46 alterations including 18 variants with unknown clinical significance (39.1%), 18 missense mutations (39.1%), 7 Indels (15.2%) and 3 large rearrangement sequences (6%) were identified. Further scanning of affected families revealed that 49% of healthy relatives harbor identical causative mutations. This is the first report of comprehensive BRCA analysis in Iranian women with early onset breast cancer. Our findings provide valuable molecular data to support physicians as well as patients for the best decision making on disease management.