Women with inherited BRCA1/2 mutations are at increased risk of breast and ovarian cancer. The reports on the prevalence and spectrum of these mutations have been primarily focused on individuals with European ancestry. A previous study on Iranian breast cancer patients reported no BRCA1/2 mutation in early-onset breast cancer with no other criteria, which is contrary to other populations. The purpose of this study was to characterize the patterns of these mutations in Iranian breast and ovarian cancer patients and evaluate the predictive efficacy of the Manchester scoring system in patients and their unaffected family members. We retrospectively reviewed the genetic testing performed for breast and ovarian cancer patients and unaffected individuals with a positive family history. The study participants were selected based on the NCCN (National Comprehensive Cancer Network) criteria (version 2.2024). A total of 376 female breast cancer patients, 49 ovarian cancer patients, and 74 unaffected individuals were enrolled in this study. In breast cancer patients, 24 (6.4%) BRCA1 and 23 (6.1%) BRCA2 mutations were detected. In ovarian cancer patients, 9 (18.5%) BRCA1 and 1 (2%) BRCA2 mutations were identified. Three (4.1%) BRCA2 mutations were identified in unaffected individuals. Seven breast cancer patients with age of cancer diagnosis ≤ 40 and no other criteria (including family history) had an underlying mutation: Four BRCA2, and three BRCA1 mutations. The Manchester score performed well, with a sensitivity of 81% and a specificity of 70%. More research is needed to clarify the hereditary component of breast and ovarian cancer in Iranian patients.