The acute antianginal effects of 5 mg and 20 mg nisoldipine were compared with 20 mg nifedipine and placebo. Maximal treadmill exercise testing was performed before and 3 hours after drug administration in 10 patients with chronic stable angina. Resting heart rate and systolic blood pressure were unchanged following low-dose nisoldipine, but 20 mg nisoldipine and 20 mg nifedipine increased heart rate and decreased systolic arterial pressure (p less than 0.05). Time (in seconds) to the onset of 0.1 mV ST segment depression was significantly prolonged after 5 mg nisoldipine (+60 +/- 53; p less than 0.05) and 20 mg nisoldipine (+100 +/- 78; p less than 0.01) but not after 20 mg nifedipine (+48 +/- 131; p = NS). Total exercise duration increased significantly following 5 mg and 20 mg nisoldipine (p less than 0.01 and p less than 0.001, respectively) but only slightly following nifedipine (p = NS). The maximal rate-pressure product was increased to a similar degree following doses of both nisoldipine and nifedipine (p less than 0.05). Nisoldipine is an effective antianginal agent which performs well in comparison to nifedipine.