Ovarian cancer is the leading cause of cancer incidence and mortality worldwide. Study shows that the use of oral contraceptives is inversely associated with the risk of ovarian cancer and is thought to be the most powerful known chemo-preventative agent. Oral contraceptive-associated risk reduction was also observed among women with a family history of ovarian cancer. Oral contraceptive reduces the risk in a duration-dependent fashion, as the beneficial effects of oral contraceptives remain for a long time even after cessation of use. This long-term protection may have significant implications for individual risk assessment and public health since the incidence of ovarian cancer rises with it.