OBJECTIVE This study sought to assess the presence and extent of inducible myocardial dysfunction during painful and painless (silent) myocardial ischemia in a homogeneous patient cohort with coronary artery disease and no previous myocardial infarction. BACKGROUND The functional significance of painless versus painful demand-driven ischemia remains controversial, with conflicting results in published reports regarding the amount of myocardium in jeopardy. METHODS Exercise echocardiography was performed in 89 patients (mean [+/- SD] age 59.3 +/- 8.2 years) with significant coronary artery disease and positive exercise stress test results. Patients were taking no antianginal medications and were classified into painless and painful cohorts after the outcome of a symptom-limited treadmill exercise test. No patients had previous coronary artery bypass surgery. Images were acquired in digital format before and immediately after treadmill exercise testing. RESULTS Fifty-eight patients had painful and 31 painless myocardial ischemia. Clinical and demographic characteristics as well as coronary artery anatomy were similar in both groups. Patients with painless ischemia achieved better exercise performance with greater exercise duration (p < 0.001) and higher maximal rate-blood pressure product (p < 0.001) than those with painful ischemia. New wall motion abnormalities were seen in 54 patients (93%) with painful versus 17 (55%) with painless ischemia (p < 0.001). Total ischemic score was greater in patients with painful than in those with painless ischemia (15.9 +/- 3.7 vs. 12 +/- 1.4, p < 0.001, respectively), with a greater number of ischemic myocardial segments in painful than in painless ischemia (101 [16%] vs. 21 [6%], p < 0.001, respectively). CONCLUSIONS Patients with painless ischemia frequently have regional myocardial dysfunction on exertion detected by echocardiography, but painful episodes are accompanied by a greater magnitude of myocardial dysfunction.