Nine patients with coronary heart disease, 8 of whom were taking adrenergic beta-blockers, were tested by dynamic (bicycle) and isometric (sitting handgrip) exercise before and 2 and 6 h after application of nitroglycerin 30 mg in an ointment, or a matching placebo ointment, over 225 cm2 surface on the chest, in a double-blind, cross-over, single dose study. Exercise time until stopping from chest pain was significantly increased (by about 20%) by active ointment, and electrocardiographic ST-depression and chest pain intensity were significantly less pronounced during exercise both 2 and 6 h after application. During seated rest, active ointment also produced a significantly lower systolic blood pressure and a significantly higher heart rate at both 2 and 6 h, whereas during handgrip, significant differences from placebo were seen only at 2 h. All patients experienced headache for at least the 6 h of the study. At a given heart rate, ST-depression was less pronounced with active ointment than with placebo.