Oral contraceptive use is the most common type of contraception. More than 300 million women worldwidetake oral contraceptives every day. However, there is a concern about the relationship with the incidenceof cancer. This analytical retrospective study aimed to investigate the relationship between the incidence ofcervical and breast cancers and oral contraceptive use in 128 Iranian patients with cervical cancer, 235 withbreast cancer and equal numbers of controls. Data were collected through interviews with an organized set ofquestions. Details were also extracted from patient files. Data were analyzed using Student’s t-test, chi-square andFisher’s exact tests, and Pearson’s correlation analysis. The result revealed correlations between both cervicaland breast cancers and history of contraceptive pills use. While cervical cancer significantly correlated withduration of use of pills, breast cancer had significant correlations with the type of oral contraceptive and age atfirst use. No significant relationships were found between the two types of cancer and age at discontinuation oforal contraceptives, patterns of use, and intervals from the last use. The use of oral contraceptives may triplethe incidence of cervical cancer and doubles the incidence of breast cancer. Therefore, performing Pap smearsevery six months and breast cancer screening are warranted for long-term oral contraceptive users.