The hemodynamic changes caused by ketanserin, an anti-hypertensive agent with S2-serotonergic receptor and alpha 1-adrenoceptor blocking properties, are reviewed in patients with essential hypertension. The hemodynamic profile associates a decrease in total peripheral resistance, an unchanged cardiac output, and a modest reflex cardiac stimulation. Whether the drug reverses the other hemodynamic abnormalities of essential hypertension, such as reduced arterial and venous compliances and increased cardiac mass, remains largely unknown. Evaluation of the changes in arterial and venous systems will be important in the view that the pharmacological profile of ketanserin could be involved in the modifications of the arterial wall observed in hypertension and atherosclerosis.