A case control study was performed including 123 patients with breast cancer diagnosis as cases and 208 healthy women as controls. for analysing obesity we had two parameters: Past BMI (with weight during a long period of patient's lifetime) and current IMC (with quantified current weight). Also other known risk factors were included. Past BMI shown increased risk both in premenopausal women: in 25.0-29.99 kg/m2 OR:7.29(CI95%:1.752-30.38); in ≥ 30.0 kg/m2 OR:23.43(CI95%:2.401-229.7); as in postmenopausal women: in 25.0-29.99 kg/m2 OR:3.33(CI95%:1.54-7.19); in ≥30.0 kg/m2 OR:6.04(CI95%:1.78-20.50). On the other hand current BMI didn't show the same association both in premenopausal women: in 25.0-29.99 kg/m2 OR:0.229(CI95%:0.053-0.99); in ≥30.0kg/m2 OR:0.369 (CI95%:0.076-1.802); as in postmenopausal women: in 25.0-29.99 kg/m2 OR:0.79(CI95%:0.35-1.85); in ≥ 30.0 kg/m2 OR:1.19(CI95%: 0.42-3.38). In conclusion, the history of obesity is associated with increased risk of breast cancer both in premenopausal and postmenopausal women.