Epidemiologic data support the hypothesis that the types of OCs used before the mid-1970s protected against most forms of benign breast disease. It is unclear whether current low-dose progestogen OCs will confer the same protection. Further studies are necessary to clarify this. For breast cancer, the relationship is more complex. It is possible that prolonged use of high-dose OCs exert a small increased risk for breast cancer development in women before age 45. Furthermore, prolonged use before a first term pregnancy may result in a small increase in risk for breast cancer before age 45. Studies evaluating the effect of current low-dose OCs are necessary to elucidate what, if any, effect they may have on breast cancer development. Furthermore, as our population ages, studies will be able to determine what effect, if any, may be present in women over age 60, those women with the highest underlying risk of breast cancer. And finally, more research of basic breast tissue physiology and the effect of endogenous and exogenous hormones on this complex organ is needed.