Germ-line mutations in BRCA1 and BRCA2 predispose to hereditary breast-ovarian cancer syndrome. In Finland, 21 different BRCA1/2 mutations have been identified and 14 of the mutations are founders that account for the great majority of all BRCA1/2 mutations. Our aim was to determine the prevalence of the 21 BRCA1/2 mutations in Finnish ovarian carcinoma families. Mutations were screened in 23 families with at least two cases of invasive epithelial ovarian carcinoma in the first-degree relatives. The families had been identified from a population-based series of 559 Finnish epithelial ovarian carcinoma patients. Fourteen of the families were site-specific ovarian carcinoma families, while breast cancer was present in nine families. Mutations were detected in five families: two had a mutation in BRCA1 and three in BRCA2. In one family, a novel, apparently disease-causing missense mutation in the BRCA2 gene had been identified previously. Thus, 26% of the Finnish ovarian carcinoma families were found to be BRCA1/2 mutation-positive. Strong ovarian cancer family history and early-onset breast cancer were strongly associated with BRCA1/2 mutation status; all families with three ovarian carcinoma cases or early-onset breast cancer (<50 years) were mutation-positive, whereas all families with later-onset breast cancer as well as the majority (9/11) of the site-specific ovarian carcinoma families with minor ovarian cancer history (i.e. two affected cases) remained mutation-negative.