Differentiating between ischemic and non-ischemic cardiomyopathy is an extremely important issue as patients with ischemic cardiomyopathy (ICM) is susceptible to have a scrimpy prognosis due to the residual ischemia, and their prognosis often changes dramatically after revascularization. Aim of this work was to compare left ventricular longitudinal function at rest and during dobutamine stress in ischemic and non-ischemic cardiomyopathy, with and without LBBB, and thus differentiating between them. Methods: Cross sectional study inclosed 75 subjects the subjects were categorized into 3 groups: Group A: contained fifteen healthy subjects (Control group), Group B: it contained therty patients (Patients have ICM) and Group C: it contained 30 patients (Patients have DCM). According to the LBBB absence or presence of, the patients were re-classified into 2 groups: Group I: inclosed 36 patients (Patients have normal conduction). Group II: inclosed 24 patients (Patients have LBBB). All patients submitted to transthoracic conventional & dobuamine stress echo Doppler study, measuring long axis function by using M-mode recording acquired at the mitral valve ring 4 angles. Systolic amplitude was calculated by gaining long axis maximum systolic displacement. The systolic velocity was acquired by spliting systolic amplitude on displacement. The pulsed wave tissue Doppler parameters (PWTD) inclosing Systolic (Sm, cm/s) and diastolic (Em and Am) velocities. Measurements were taken at baseline and within dobutamine infusion. Coronary angiography was done.