In order to evaluate the usefulness of urapidil in the treatment of severe hypertension and in the long-term treatment of essential hypertension, two open multicentre studies were performed. In one study, 34 outpatients with diastolic blood pressure exceeding 105 mmHg following treatment with a combination of a diuretic and a sympatholytic or a diuretic and a beta-blocker were additionally given 15-60 mg urapidil twice a day for 8 weeks or more. The responder rate was 73.5%. The pulse rate did not change throughout. Side effects such as dizziness and malaise were observed in five patients (14.7%), but they were slight and did not require withdrawal of treatment. The other study included 95 outpatients with essential hypertension (World Health Organization stages I or II), 15-60 mg urapidil twice a day for 1 year or more in monotherapy (n = 48) or in combined therapy with a thiazide (n = 47). Under both therapies, diastolic blood pressure was reduced significantly at week 4, further reduced at week 12 and remained stable until week 52. Responder rates were 82.9% in monotherapy and 78.4% in combined therapy. Two patients (4.2%) taking monotherapy and six patients (12.8%) taking combined therapy were withdrawn due to inadequate blood pressure control or to side effects. These results indicate that urapidil is useful in severe and in long-term hypertension.