The great importance of knowing the risk factors for breast pathology in order to reveal the risk categories is well known. In many geographical areas breast cancer is the most common female neoplasm. Recent Italian statistics point out that every year 83 women out of 100,000 develop breast cancer and that its incidence is increasing. Every year in Italy 10,000 women die of breast cancer. In our retrospective study 146 women suffering from breast cancer, treated in our Institute from 1970 to 1993, were enrolled. We excluded 4 patients, surgically treated in another Institute and 35 who presented a second or a third gynaecological cancer. We considered age, menarche, parity and menopausal age in all patients in order to evaluate the association of these risk factors with breast cancer development. The average age when neoplasm was first diagnosed was 53.07 years (between 30-84 years), with a 9.4% incidence in patients under 35 years old. In 41.1% of the cases, menarche was present under 12 years and in only 14.1% after 14 years, therefore confirming the reduction of mammary cancer risk in women with late menarche. Twenty one point five per cent of the patients were nulliparous. In our case series no protective factor seemed to be related with 1 or 2 pregnancies (43.9%). The menopausal average age was 50.2, with an average fertile life period of 37.1 years. Our study also considered the location of the primary neoplasia (60.7% in the upper-outer quadrant), the tumor size (3.08 cm average diameter) and the histological type (81.3% ductal form).(ABSTRACT TRUNCATED AT 250 WORDS)