Hormonal contraception has a protective effect over ovarian and endometrial cancer development. Relative risk of ovarian cancer decreases by approximately 20% for each 5 years of use; it is approximately 50% for 15 years of use and decreasing with further use. The protective effect gained declines as time passes from its last use, but a significant effect remains a long time after ceasing. The effect is independent from the type of formulation used. Hormonal contraceptives do not protect from mucinous types of ovarian tumours. Relative risk reduction of endometrial cancer is even higher; the estimated relative risk decrease is approximately 50% with 4 years of use, approximately 70% with 12 years of use and decreasing with further use. After ceasing oral contraception, the risk begins to rise from its reduced levels but it is still approximately 50% even after >20 years after its last use. Hormonal contraception could be used for primary protection from ovarian and endometrial cancer development.