Doxazosin is a long-acting selective alpha 1-adrenoceptor antagonist structurally related to prazosin. Like prazosin, doxazosin exerts its antihypertensive effect by reducing total peripheral resistance by selective postsynaptic alpha 1-blockade, without reducing cardiac output, and similarly, doxazosin appears to have a negligible effect on heart rate. Doxazosin differs from prazosin in that its long half-life enables once-a-day oral administration. Doxazosin significantly lowers both standing and supine blood pressure and appears to maintain this antihypertensive effect over a 24-hour dosing interval. Doxazosin 1 to 16 mg once daily has been found to be comparable in efficacy to atenolol 50 to 100 mg and prazosin 1 to 20 mg daily. Characteristic of alpha 1-adrenoceptor antagonists, doxazosin also has favourable effects on the plasma lipid profile in that it decreases total cholesterol and triglycerides, and increases high density lipoprotein (HDL) cholesterol as well as the HDL/total cholesterol ratio. Although further long term trials are needed to clarify the role of doxazosin in multidrug regimens in more severe hypertension, it appears to be a suitable drug for consideration as first-line therapy in mild to moderate essential hypertension.