Background: Complete Left bundle branch block increases the risk of cardiac mortality, and prognosis is primarily determined by the underlying CAD. Because the presence of complete LBBB makes the noninvasive identification of CAD less informative, patients with complete LBBB often are referred for coronary angiography to assess the presence and severity of CAD. Objective: We purposed to determine the relationship between Left bundle branch block (LBBB) and Coronary artery disease (CAD) site, severity and CAD risk factors. Patients and methods: Eighty patients with LBBB were sorted into two groups based on coronary angiography (CA) findings: Group 1 – 56 patients with CAD (stenosis ≥70% in ≥1 epicardial vessel); and Group 2 – 24 patients with normal coronaries. Results: Our observations confirm male preponderance of LBBB and affirm hypertension and diabetes as common risk factors for coronary artery disease within this subpopulation. So these risk factors can be considered as a strong predictor of CAD in LBBB. Cardiac echo data suggests that LBBB and CAD are associated with regional hypokinesia and decreased EF. The most frequently diseased vessel was LAD, followed by LCX then RCA. Our study CA showed single vessel disease (SVD) in 37 subject (46.3%), two vessel disease (2VD) in 16 subjects (20%), three vessel disease (3VD) in 3 subjects (3.8%) and normal vessels in 24 subjects (30%). So, SVD frequency was high in our study. Conclusion: The risk for left ventricular dysfunction and single vessel disease more commonly Left anterior descending artery involvement had increased in the presence of LBBB in ECG. Coronary angiography present only in tertiary centers which considered as a major and invasive diagnostic tool for CAD so selection criteria is required to predict patients with LBBB who are prone to be at risk of CAD and need this invasive procedure, on the other hand avoid CAD over diagnosis, unnecessary admissions to hospital and anti anginal drugs consumption. Key words: Left bundle branch block, Coronary artery disease, Ischemic heart disease, Left ventricular dysfunction, Coronary angiography