Protection against ovarian cancer, the most lethal of female reproductive tract cancers, is one of the most important benefits of oral contraception. Because this cancer is detected late and prognosis is poor, the impact of this protection is very significant. The risk of developing epithelial ovarian cancer in users of oral contraception is reduced by 40% compared to that of nonusers. This protective effect increases with duration of use (taking 5-10 years to become apparent) and continues for at least 10-15 years after stopping the medication. This protection is seen in women who use oral contraception for as little as 3 to 6 months, reaches an 80% reduction in risk with any more than 10 years of use, and is a benefit associated with all monophasic formulations, contain the little dose formulations. Again, the multiphasic and new progestin products have not been in use long enough to yield any data on this issue, but because ovulation is effectually inhibited by these formulations, protection against ovarian cancer should be exerted.