We reviewed clinical characteristics, treadmill exercise tests, and thallium-201 (Tl-201) scintigraphies of 31 patients experiencing coronary artery spasms examined between January 1991 and September 1992. We divided the patients into two groups: a single-vessel—spasm group (group S, n = 21) that consisted of patients with one spasmodic vessel, and a multivessel-spasm group (group M, n = 10) that consisted of patients with two or more spasmodic vessels. There were 7 patients (33%) in group S and 7 patients (70%) in group M who suffered from effort-induced angina, 12 patients (57%) in group S and 8 patients (80%) in group M revealed significant ST-segment depression on exercise electrocardiogram tests, and 13 patients (62%) in group S versus 8 patients (80%) in group M revealed Tl-201 scintigraphy findings positive for ischemia. No statistically significant differences were found. In 2 patients (10%) in group S and 6 patients (60%) in group M, perfusion defects were shown on Tl-201 scintigraphy ( P < 0.05). Patients with multivessel spasms exhibited exercise-induced myocardial ischemia more often than patients with single-vessel spasms, which suggests that exercise-induced coronary spasm tends to occur more often in patients with multivessel spasms than in patients with single-vessel spasms.