To determine whether oral contraceptives (OCs) can be used safely in a continuous manner to prevent monthly withdrawal bleeding. Search of MEDLINE (1966-2000), International Pharmaceutical Abstracts (1970-2000), and the Internet. Several prospective studies have assessed the efficacy of continuous cycle OCs in preventing monthly withdrawal bleeding. Monophasic OCs are useful for this purpose. In studies using traditional OC regimens as a control, patients receiving continuously administered OCs experienced more breakthrough bleeding and spotting. Continuous use of OCs decreased headache and other menstruation-associated symptoms. No long-term trials have assessed the impact of continuous use of OCs on risk of cancer, thromboembolic disease, or fertility, concems raised by opponents of the method. From the data available, continuous use of OCs is an effective method for delaying withdrawal bleeding. Long-term safety data are not available.