The value of exercise testing in patients with right bundle branch block (RBBB) is uncertain. A retrospective review of 3609 patients who underwent exercise testing identified 163 (4.5%) with preexisting RBBB. After excluding those with coronary artery bypass graft(s), 133 patients remained and 48 (36%) had a prior myocardial infarction. Angiograms were available for 30 (23%) patients. After a mean follow-up of 33 ± 23 months, seven patients had a fatal or nonfatal myocardial infarction. Twenty five (19%) patients had ≥1 mm of non-upsloping ST depression in leads V 5 or V 6. With angiographic disease or previous myocardial infarction used as endpoints of coronary artery disease, the exercise test had a sensitivity of 27% ( 16 56 ), a specificity of 87% ( 67 77 ), and a predictive accuracy of 62% ( 82 133 ), ( χ 2 = 4.04, p = 0.04). There were 24 deaths, a 10% annual mortality rate. Univariate analysis of clinical, exercise, and angiographic data revealed that nonsurvivors had a lower peak systolic blood pressure, a lower exercise capacity in METS, and a higher prevalence of coronary artery disease ( p = 0.0001, p = 0.02, p = 0.03, respectively). Left ventricular ejection fraction and the amount of additional ST depression during exercise did not differ significantly ( p = NS). Receiver operating characteristic curve analysis revealed that systolic blood pressure (area = 0.741, z = 5.22, p < 0.001) and exercise capacity (area = 0.66, z = 3.12, p = 0.009) were predictive of mortality, whereas additional ST depression during exercise (area = 0.588, z = 0.70, p = 0.24) was not. Therefore in individuals with preexisting RBBB the exercise test is insensitive, but specific, for diagnosing coronary artery disease and mortality is related to the presence of coronary artery disease. Systolic blood pressure and exercise capacity are stronger predictors of mortality than is exercise-induced ST depression.