e12513 Background: Family history (FH) of breast cancer (BC), ovarian cancer (OC), and individual features (IF), like early age of onset, bilateral BC, coexistence of BC and OC, and triple negative BC (TNBC) younger than 50 years, are suspicion criteria of hereditary BC. Although it is assumed in the literature that 15-30% of BC cases can be familial BC (FBC), only 5-10% of BC are hereditary, explained by a germline mutation in BRCA1 or 2. Moreover, there is no international consensus to define FBC (e.g. number of relatives affected, age of onset), in contrast with, e.g. Lynch syndrome and Amsterdam/Bethesda criteria, in order to offer genetic counseling. In Spain, there are not population-based studies analyzing the real percentage of BC with familial and/or individual high risk features. Methods: A retrospective study based on 10,641 Spanish BC patients diagnosed from 1998-2001, collected in the “El Álamo III project”, was conducted. Specific data regarding FBC were analyzed: IF (age of onset, bilateral breast cancer, ovarian cancer and TNBC; and FH features (first and second degree relatives with BC and /or OC). Results: The Table summarizes the results. Conclusions: 21% of BC patients in Spain diagnosed from 1998 to 2001 have at least one relative with BC and/or OC. In addition, 2.8 % of patients with no FH of BC/OC fulfill high risk criteria. However, several study characteristics, such as 18% patients with no FH recorded, and lack of data regarding age of affected relatives, limit the interpretation of these results, being necessary to improve the family data collection in further “El Álamo” project studies. [Table: see text]