A histological analysis was conducted in 138 female breast cancer patients, and the results were classified in accordance with "Histological Typing of Breast Tumours" (WHO, Geneva 1981). Since about half of these tumors showed more than one histological type of carcinoma, a simplified classification system with four groups was adopted. When patients were categorized according to the number and degree of kinship of their relatives with breast cancer, no specific association with the histological types was found. Familial tumors also encompassed a wide spectrum of histopathologic diagnoses. This suggests the absence of a histological marker in familial breast cancer. Pedigrees of all the patients were then analyzed, special emphasis being placed on relatives suffering from the same and other malignancies. It was found that 13.8% of the probands had at least one first-degree relative with breast cancer and that, compared with the tumor spectra in the male and female population, there was a significantly higher number of esophageal carcinomas in the fathers, of stomach cancers in the uncles and grandfathers, of brain tumors in the mothers, and of sarcomas in the brothers. An accumulation of the same tumors, especially stomach cancer and tumors related to the SBLA syndrome, was observed in families of index patients with tubular or medullary breast cancer. The SBLA syndrome is a complex familial cancer syndrome characterized by a proclivity to Sarcomas, Breast cancers, brain tumors, Lung and laryngeal cancers, leukemia, and Adrenocortical carcinomas.