The Veterans Affairs Vasodilator-Heart Failure Trials (V-HeFT I and II) provided information about heart failure treated with conventional therapy, and evaluated the long term efficacy of vasodilators. In V-HeFT I, the combination of hydralazine and isosorbide dinitrate provided a beneficial effect on prognosis in heart failure. V-HeFT II demonstrated that enalapril had a more favourable effect on 2-year survival than a combination of hydralazine plus isosorbide dinitrate. However, the hydralazine-isosorbide dinitrate combination exerted the most favourable short term impact on exercise performance and left ventricular ejection fraction. The V-HeFT studies showed that, although not all vasodilators are alike, their differing effects might be beneficial when used in combination. Determination of the potential additive effect of the calcium antagonist felodipine, a vasodilator, when used in combination with an ACE inhibitor, is the major goal of V-HeFT III.