The selective beta 1 adrenoceptor agonist denopamine was studied for its effectiveness in abolishing active vasospastic angina in 10 patients without obstructive coronary artery stenosis. All patients had anginal attacks at least once a day during the 3-day placebo period. Denopamine, 40 mg/day, completely abolished the attacks in 7 patients (efficacy 70%). Denopamine reduced the mean daily number of anginal attacks and nitroglycerin consumption in comparison with placebo (0.56 +/- 1.23 vs 2.20 +/- 1.27; p < 0.005 and 0.10 +/- 0.24 vs 1.60 +/- 1.93; p < 0.05, respectively). Aggravation of anginal attacks was not seen in any patient. During placebo period, anginal attacks were provoked in 6 of the 10 patients who received exercise stress test, and in 6 of the 7 patients who received the cold pressor test in combination with hyperventilation. Denopamine prevented anginal attacks induced by exercise stress tests in 4 of the 6 patients (67%) and that induced by the cold pressor test in 4 of the 6 patients (67%). There were no severe adverse effects during denopamine therapy. These results suggest that 1) denopamine is a safe and effective medication for vasospastic angina; 2) beta 1 adrenoceptors may play an important role in the prevention of coronary artery spasm.