Obesity has a negative impact on female reproductive health. It has been found to be linked to ovarian dysfunctions that manifest themselves as anovulation, menstrual cycle disorder, and almost a three-fold increase in the rate of endocrine infertility. Female obesity increases the risk of breast and endometrial cancer. Despite a great number of reports on reproductive dysfunctions in obese women, their genesis has not yet been precisely determined. A great number of papers on the relationship between hyperinsulinemia and ovarian hyperandrogenism have been published recently. Most investigators acknowledge that insulin resistance and hyperinsulinemia give rise to polycystic ovary syndrome. This review details the pathogenetic aspects of the impact of obesity on reproductive system function and sex hormone metabolism in women.