Morbid obesity is about twice as common in women as in men. Approximately 80-85% of women who have undergone weight loss surgery are of childbearing age, and the prevalence of PCOS in women of childbearing age is approximately 6-10%. Of these, more than 50% of women with PCOS are overweight or obese. The prevalence of anovulation is higher in obese PCOS patients compared to low weight PCOS patients. The American Society for Reproductive Medicine requires that the following two criteria be met for the diagnosis of PCOS: menstrual sparseness or anovulation, clinical or biochemical manifestations of hyperandrogenism and polycystic ovaries. However, other conditions caused by hyperandrogenism must be excluded. Pathophysiology of PCOS The pathophysiology of PCOS is complex, multifactorial and incompletely understood. Excess adipose tissue in obese individuals can lead to insulin resistance and a hyperinsulinized state. Insulin in turn stimulates androgen production by ovarian follicular membrane cells and also inhibits hepatic synthesis of sex hormone binding globulin. This results in a functional hyperandrogenic state that inhibits normal follicular maturation. Obesity and anovulation are independently associated in women of reproductive age. Efforts should be made to instill in women who are obese and/or diagnosed with PCOS the idea of losing weight in the first place. Studies evaluating the effect of lifestyle changes on obese women with PCOS have shown that a 5-10% weight loss improves insulin sensitivity and restores ovulation. Conclusion Currently, the American College of Obstetricians and Gynecologists does not recommend weight loss surgery for fertility treatment. Although the current literature is flawed, there does appear to be evidence that weight loss after weight loss surgery has an impact on fertility. Further research is still needed to determine the optimal bariatric surgery modality, time to conception after surgery, and fertility success rates.