High rates of adolescent pregnancy remain a challenge for health care providers. For most sexually active adolescents, pregnancy is unintended. Emergency contraception, also called the "morning-after-pill" or postcoital contraception, is a way to prevent pregnancy after unprotected intercourse. In the United States, three forms of emergency contraception currently are available: high-dose combination estrogen and progestin pills, high-dose progestin-only pills, and postcoital insertion of a copper intrauterine device. The postcoital intrauterine device is used infrequently. When emergency contraceptive pills (ECPs) are taken within 72 hours of unprotected intercourse, they reduce the risk of pregnancy by at least 75%. However, they are most effective if taken within 24 hours of coitus. Eleven brands of pills currently are marketed in the United States that conform to the regimens approved by the Food and Drug Administration (FDA) for this indication. Recently, two prepackaged ECPs were approved by the FDA. The only medical contraindication to prescribing ECPs is pregnancy. The most common side effects are nausea and vomiting, followed by menstrual disturbances, breast tenderness, abdominal cramping, dizziness, headache, and mood changes. Because vomiting can compromise the efficacy of ECPs, routine pretreatment with an antiemetic is recommended. Primary care providers can reduce unintended adolescent pregnancy by routinely counseling adolescents at all office visits about the existence of emergency contraception and by prescribing it in advance and over the telephone.