Hormone therapy (HT), in peri- and postmenopause has been associated with a modest increase in the risk of breast cancer. Hormones play a major role in tumorigenesis of breast cancer, and reproductive factors are known to influence breast cancer risk. Female sex steroids are used for contraception or menopause treatment by women of reproductive age and postmenopausal women respectively. This review reports recent published epidemiological evidence and randomised trials which examined the effect of HT on the risk of breast cancer.