Patients with left bundle branch block (LBBB) and concomitant coronary artery disease (CAD) have a worse prognosis than those with LBBB without CAD. In addition, subjects with CAD and concomitant LBBB have a higher cardiovascular mortality than those with a similar extent of CAD but without LBBB. Because the presence of LBBB makes the noninvasive identification of CAD problematic, patients with LBBB often are referred for coronary angiography to assess the presence and severity of CAD. To determine the clinical and demographic variables that might help identify those with CAD, we analyzed data from 336 consecutive patients with LBBB referred for coronary angiography. Of the 336, 54% had CAD. In conclusion, those with CAD were likely to be older, Caucasian, and men; they were more likely to have angina pectoris, myocardial infarction, and diabetes mellitus; and they were more likely to have a left ventricular ejection fraction <0.50. In contrast, patients with heart failure were less likely to have CAD.