The benefits of antihypertensive therapy in pregnancy remain uncertain. Blood pressure control to prevent or correct severe hypertension can avert maternal target organ damage and may allow obstetricians to prolong pregnancy or avoid hospitalization. Several factors limit the conclusions derived from systematic review of the available studies, including failure to distinguish among women with preeclampsia, gestational hypertension, or whose hypertension antedated pregnancy. As well, the application of consensus guidelines is limited by the unfortunate tendency to measure blood pressure by use of oscillometric devices rather than auscultation. We review the basis for using specific antihypertensive drugs in pregnancy and highlight important shortcomings in therapeutic knowledge that should be addressed in future studies.