Objective: The aim of this study was to determine body composition, gynecological, and obstetric data, sex hormones, and prolactin serum levels in pre-(PREW) and postmenopausal women (PMW) with breast cancer (BC) and compare them with a control group (CG) of healthy women. Methodology: BC patients without treatment or use of hormone replacement therapy, or hormonal birth control, and without data of metastasis were included. CG was matched for age, BMI, and menstrual cycle status. FSH, LH, E 2 , progesterone, testosterone, and prolactin (PRL) were measured using radioimmunoassay kits. Comparisons between BC and CG were made with "t" tests, and with the Mann-Whitney U-test; χ 2 test was used to compare the qualitative variables between the groups. Results: Seventy-two patients with BC, and 74 CG women were evaluated. Both groups presented overweight data, BMI (kg/mt 2 ) = 27.21 ± 5.51 vs. 28.40 ± 4.66, p = ns, for BC patients and CG, respectively. In PREW, the age at menarche was later in BC patients compared to the CG (13.3 ± 1.36 years vs. 12.41 ± 1.27 years, p = 0.005). The PMW with BC presented a higher age at menarche and menopause compared to the women of the CG (13.51 ± 1.48 vs. 12.91 ± 1.41, p = 0.09, and 49.03 ± 2.86 vs. 45.5 ± 8.78, p = 0.03, respectively). PRL levels were significantly higher in PMW with BC, in comparison with the CG; median and minimum and maximum values (min-max) were: 14.7 ng/mL (3.6 -52.7) vs. 5.9 ng/mL (1.9 -33.3), p = 0.005). A higher percentage of PMW with BC (26.0% vs. 7.1%, χ 2 = 5.57, p = 0.01) presented hyperprolactinemia (PRL serum levels > 20 ng/mL