Coronary spasm is an important etiologic mechanism in the pathogenesis of myocardial ischemia. Provocative test of coronary spasm during coronary arteriography is clinically useful. The ergonovine test has gained widespread use, and we have examined the efficacy and safety of intracoronary ergonovine application with a fixed dose of 16 micrograms. We studied 119 patients undergoing coronary arteriography. Coronary spasm was induced in 34 cases by intracoronary administration of 16 micrograms of ergonovine maleate. Coronary spasm was readily resolved by intracoronary administration of isosorbide dinitrate. None of the cases negative to the intracoronary ergonovine applications could be induced by additional systemic administration of 0.4 mg of ergonovine. Side effects of ergonovine such as elevation of blood pressure, headache and chest symptoms were infrequent in the intracoronary ergonovine test. We conclude that our method of intracoronary ergonovine application is sensitive and safe for the diagnosis of coronary spasm.