Background: Much controversy has been generated about pre- and post-menopausal breast cancer patients and investigators have sought to identify whether risk factors differ between these two groups. In Brazil, breast cancer is an important cause of death among women and there are few analytical studies concerning pre- or post-menopausal comparisons. Methods: A case-control study was carried out at the Federal University Hospital, Belo Horizonte, Brazil, to determine if selected socio-economic and reproductive risk factors for breast cancer differed between pre-menopausal and post-menopausal women. Cases were 300 women with breast carcinoma and controls were 600 women with other benign diseases matched for age and date of diagnosis, admitted to the same hospital during the same period (1978–1987). Univariate and multivariate conditional logistic regression analyses were performed. Results: Multivariate analysis showed no differences in breast cancer risk in pre- and post-menopausal women (risk factors were similar in direction and magnitude). Occupation, irregular menstrual cycles, parity, history of breast cancer in at least one first-degree female relative, and oral contraceptive use had similar associations in both groups. Conclusions: The present study indicates that breast cancer diagnosed before and after menopause has a similar risk profile.