Calcium channel antagonists are widely prescribed in obstetrics and gynecology for blood pressure control and tocolysis. Concerns have recently arisen regarding the safety of these agents. Several studies found that short-acting forms of calcium channel blockers were associated with increased cardiovascular mortality, malignancy, and gastrointestinal bleeding. A recent meta-analysis found a significant increase in the risk of mortality in patients treated with a short-acting form of nifedipine. Another subgroup analysis of an observational study of older hypertensive patients found a significantly increased risk of cancer and gastrointestinal hemorrhage in patients prescribed calcium channel blockers. Both in vitro and small human in vitro series have reported a potential for cardiac toxicity in pregnant women treated concomitantly with calcium channel blockers and magnesium sulfate. Until additional data are available, we suggest that when calcium channel blockers are used in obstetrics and gynecology, the long-acting variety be prescribed. Concurrent use of calcium channel blockers and magnesium sulfate should be undertaken cautiously because of the potential for synergistic depression of cardiac function.