To clarify the prognostic implications of exercise induced silent myocardial ischemia (SMI) in patients with angina pectoris, the clinical characteristics and long-term prognosis after coronary angiography in 379 patients without prior myocardial infarction were investigated. According to the results of treadmill testing and/or Tl-201 exercise imaging after medical treatment, 50 patients with negative for ischemia were classified as control group, 110 patients with exercise induced SMI were classified as the SMI group, and 187 patients with painful ischemia formed the PI group. Thirty-two patients were excluded because of inconclusive exercise results. Single vessel disease and vasospastic angina were more frequent in the control group than in the SMI and PI groups. But there were no differences in baseline characteristics and extent of coronary lesions between the latter two groups. Heart rate, systolic blood pressure and rate-pressure product at end point in treadmill testing were higher in the control and SMI groups than in the PI group. The mean follow-up period was 4.8 years, and follow-up was completed in every case. Cardiac events, including cardiac death, nonfatal myocardial infarction and readmission from severe angina, occurred in 25 patients of the SMI group, 43 of the PI group and 7 of the control group. Cumulative cardiac event curves did not show any statistically significant difference between the SMI and PI groups. We conclude the presence or absence of angina during exercise test is no longer the principal prognostic index for determining a patient's risk of cardiac events.