The effects of ketanserin on blood pressure and well-being were investigated in 188 patients, aged 41–82 years, with mild to moderate essential hypertension. At entry, 107 were untreated, 42 were taking the diuretic combination hydrochlorothiazide (50mg/day) plus amiloride (5mg/day) and another 39 were taking the ß-blocker atenolol (100mg/day). A single-blind, 4-week placebo run-in period was followed by 12 weeks' oral ketanserin treatment at 20 or 40 mg twice a day. This regimen significantly reduced systolic and diastolic blood pressures in each group. Response rates were greater in patients aged over 60 years. Compared with placebo, sleep disturbances, daytime fatigue and overall weakness decreased during ketanserin treatment (P<0.05 for all), but the incidence of dry mouth and stuffy nose increased. In patients older than 60 years there was a greater reduction of complaints than in younger patients. Ketanserin proved effective and well tolerated, improving peripheral circulatory symptomatology, particularly in older patients and those with a good blood pressure response.