Dilevalol, the RR-stereoisomer of labetalol, is a non-cardioselective beta-adrenoceptor antagonist with substantial partial beta 2-agonist and negligible alpha 1-blocking activity. Reduction in blood pressure during dilevalol administration is associated with peripheral vasodilatation, and heart rate remains essentially unchanged. Following oral administration, dilevalol is completely absorbed. Once-daily administration is possible, due to a long elimination half-life. Large well-controlled trials reveal that dilevalol is equivalent in antihypertensive efficacy to metoprolol, the ACE inhibitors captopril and enalapril, and the calcium antagonist nifedipine. Smaller noncomparative and comparative trials demonstrate the blood pressure-lowering effects of dilevalol and suggest an efficacy at least equivalent to that of the 'pure' beta-blockers atenolol and propranolol and the alpha 1-blockers urapidil and doxazosin. Dilevalol appears to be well tolerated, the most frequent adverse effects being dizziness, headache and diarrhoea in only about 7% of patients each. Unlike alpha 1-blockers and labetalol, dilevalol is not commonly associated with orthostatic hypotension. Thus, data suggest that dilevalol, with its distinctive pharmacological profile, is likely to be a useful addition to the options currently available for treating patients with mild to moderate essential hypertension.