Hypertension in pregnancy remains a major cause of maternal and fetal morbidity and mortality. It is a late manifestation of a multifactorial, multisystem disease, initiated very early in pregnancy, the features of which suggest an inadequate maternal response to pregnancy. There is a genetic susceptibility to pre-eclampsia. Endothelial cell dysfunction in response to an unknown factor(s) may evoke some of the hormonal anomalies. In established severe disease there is volume contraction, reduced cardiac output, enhanced vascular reactivity, platelet exhaustion and disseminated intravascular coagulation in addition to the hypertension. Delivery is associated with resolution of the hypertension. Pharmacological treatment is most suitable for early-onset, severe disease when an attempt to delay delivery is indicated. Methyldopa or beta-blockers and/or vasodilators may be used. ACE inhibitors are contra-indicated. Low-dose aspirin may be useful in prophylaxis.