The association between oral contraceptives and cancer is updated in this review considering recent studies on benign and malignant breast cancer and ovarian cancer and cysts uterine leiomyomas and trophoblastic disease benign and malignant liver tumors cervical pituitary and endometrial cancer and menopausal estrogens. The review begins with a discussion of investigative methods and epidemiological approaches the most common of which are case reports and tumor registries; disease rates and trends; retrospective case comparisons; and prospective cohort studies. While increasingly sophisticated methods are being applied and the lag time is now beyond that needed to detect carcinogenesis US women have been taking pills with 50 mcg or less of ethinyl estradiol and 1 mg or less of progestin for only 15 years and cancer studies do not reflect this fact. High doses of progestins (>1 mg) protect against benign breast disease; reports are conflicting about breast cancer suggesting that long durations of use before 1st term pregnancy may confer higher risk. While the most important risk factor for cervical cancer is infection with human papilloma virus risk of cervical cancer is heightened by oral contraceptive use in proportion to duration. Combined pills protect against both ovarian cysts and neoplasms; multiphasics may not be as protective against cysts but even past use of pills maintains protection against cancer. Recent data are suggestive of a protective effect of oral contraceptives against uterine fibroids. Low dose pills are not longer considered contraindicated for women having recently had a molar pregnancy removed. While it is known that long-term unopposed or sequential estrogens increase risk of endometrial adenocarcinoma combined pills confer a significant protective effect after 1 year of use. Benign and malignant liver tumors are an extremely rare condition enhanced by long-term use of oral contraceptives. Regression of the adenomas usually follows discontinuation of the pill; whether hepatocellular carcinoma arises from adenoma is yet unproven.