Background: Many factors influence the prognosis of patients with (CHF), among these; more attention has been focused on the Role of left Bundle Branch Block (LBBB). The present study was performed to find out the prevalence of CHF in LBBB patients.Methods: In this cross-sectional study, 246 were diagnosed consecutive patients with LBBB pattern in ECG during July 2004 until October 2006 at Imam Ali Heart Hospital, in Kermanshah. At the first step ECG was recorded and according to its result, chest X-ray and echocardiography were obtained if necessary. Data analysis was made using dependent sample t-test and P£ 0.05 was considered significant.Results: 246 consecutive patient with mean age 64± 10 years and the age range of 38-85 years old were studied. 46% of patients were men and 54% women. There was no statically difference between the mean age of men and women with CHF. Etiology of LBBB in this study included; CAD, Hypertension dilated cardiomyopathy and valvular heart disease. Significant difference was seen in LV dysfunction between men and women (P£ 0.05). EF for men was 35% and for women was 37.9% other wise, relation between duration complex of QRS and reduction in EF was statically significant.Conclusion: We concluded that the incidence of wide QRS is very high in CHF patients, and patients with LBBB were associated with a clinical and homodynamic feature of greater impairment of cardiac function especially in those patients with duration of QRS complex more than 140 MS.