Genetic, cultural and environmental factors are influences shared in familial breast cancer. The objective of this study was to evaluate the prevalence of familial breast cancer and its association with social and clinical characteristics of women. A hospital-based descriptive study was made, and 300 patients with the diagnosis of breast cancer, made in 1992, were investigated. 17,4% of the women had a history of familial breast cancer. The presence of a positive history for familial breast cancer was associated with high social level for post-menopausal women. Age at diagnosis was older for women whose affected relative was their sister, not their mother. The need for the continuing efforts of epidemiologists, pathologists and geneticists to recognize the explanatory model of the disease is emphasized.