The hypertensive effect of urapidil, a new antihypertensive agent that acts via central and peripheral alpha-adrenoceptors, has been compared with that of metoprolol in 40 patients with mild essential hypertension. Blood pressure was significantly reduced by both drugs, while the heart rate was reduced only after metoprolol. The increases in systolic blood pressure and heart rate caused by three progressive work loads of bicycle exercise were not affected during urapidil, whereas both were reduced by metoprolol. A slight reduction in forced expiratory volume was observed in some patients during treatment with the beta-blocker. There was no case of orthostatic hypotension during urapidil administration, despite its alpha1-blocking action. Side-effects were rare and negligible with both drugs.