Millions of women in the United States and abroad use oral contraceptive pills. These popular contraceptives are the most common reversible birth control method in the United States, and a wide variety of pills are available for prescription. Oral contraceptives provide safe and effective protection against pregnancy and offer several noncontraceptive benefits. Over the years, advances in the laboratory and knowledge gained through epidemiologic data promoted the development of new contraceptive preparations. Generations of oral contraceptives emerged over time, containing lower doses of estrogens and new and novel progestins. The current review discusses the clinical characteristics of oral contraceptives, with emphasis on basic pharmacology and the evolution of various contraceptive formulations and regimens.