A double-blind, randomised, parallel-group trial was conducted in patients with essential hypertension in British general practices, of nebivolol 5 mg, atenolol 50 mg, and placebo each given once daily. Both active drugs, in comparison with placebo, caused highly significant and similar reductions in systolic and diastolic pressures without orthostatic effect, and small significant falls in heart rate. Both active drugs were well tolerated, nebivolol marginally more so. Nebivolol, a long-acting, cardioselective, vasodilating beta-blocker which acts partly via the l-arginine/nitric oxide mechanism, appears potentially valuable for the treatment of hypertension.