The current study was designed to evaluate the prevalence of BRCA1 and BRCA2 germline mutations in Greek moderate- and low-risk individuals with respect to clinicopathological phenotype and clinical outcome of breast cancer. Ninety-four consecutive individuals were prospectively recruited from two University Breast Cancer Clinics (Hippokrateion Hospitan and Laikon Hospital) between 1989 and 1999 and were categorized as moderate-risk and low-risk individuals for carrying BRCA1/2 germline mutations. To identify the underlying mutations, protein-truncation test and single-strand conformation polymorphism methods were used, followed by direct sequencing. Three novel BRCA1 missense mutations, one novel BRCA1 intronic deletion, three novel (previously reported) BRCA2 truncating mutations, and one novel BRCA2 missense mutation were identified in the moderate-risk group of individuals studied. The BRCA1/2 missense mutations as well as the single intronic variant identified were designated as unclassified genetic variants. Two BRCA1 unclassified genetic variants (missense mutations) were detected in two of the three (66.7%) male breast cancer patients analyzed, while the third one was identified in a sporadic (low-risk) breast cancer patient. Clinicopathological characteristics of breast carcinomas originating from BRCA1/2 heterozygotes were consistent with those already reported and not different from those observed in BRCA1/2 mutation (-) breast cancer patients. Furthermore, BRCA1/2 mutation carriers presented an excellent 4.5-year overall survival (100%). Our results reveal the unique characteristics of BRCA1/2 mutation status, genotype-phenotype correlations, and prognosis, in moderate- and low-risk individuals of Greek ancestry. Breast cancer due to mutations in BRCA1 and BRCA2 genes appears to be a heterogeneous syndrome in the Greek population.