Background: Differentiating between ischemic and non-ischemic cardiomyopathy is a extremely important issue as patients with ischemic cardiomyopathy (ICM) is susceptible to have a scrimpy prognosis due to the residual ischemia, their prognosis often changes dramatically after revascularization. Aim of this work was to compare left ventricular longitudinal function at the rest and through dobutamine stress in ischemic cardiomyopathy, non-ischemic cardiomyopathy, with or without LBBB, so distinguish between them. Methods: Cross sectional study enclosed 75 subjects, the subjects were categorized into 3 groups: Group A contained fifteen healthy subjects (Control group), Group B contained thirty patients (Patients have ICM) and Group C contained 30 patients (Patients have DCM). According to the LBBB absence or presence, the patients were re-classified into 2 groups: Group I enclosed 36 patients (Patients have normal conduction). Group II enclosed 24 patients (Patients have LBBB). All patients submitted to transthoracic conventional & dobuamine stress echo Doppler study and measuring long axis function by using M-mode recording acquired at the mitral valve ring 4 angles. Systolic amplitude was calculated by gaining the long axis maximum systolic displacement. The systolic velocity was acquired by Splitting systolic amplitude on displacement. The pulsed wave tissue Doppler parameters (PWTD) inclosing Systolic (Sm, cm/s) and diastolic (Em and Am) velocity. Measurements were taken at baseline and within coronary angiography and dobutamine infusion. Results: Patients having DCM had a significant increase in LVESD, HR and LVEDD and a significant decrease in EF compared with ICM patients (P=0.0413, 0.0001 and 0.0008) respectively and elevated WMSI (p= 0.016) at using dobutamine with low dose. long axis motion (amplitude and velocity) and systolic velocity (Sm) by Pulsed tissue Doppler (PWTD) were significantly increase in DCM patients comparing with ICM patients (< 0.00001). long axis parameters were significantly decrease in LBBB patients comparing Group I (< 0.00001). No significance difference had noticed between wall motion score index in ICM patients and DCM patients at the rest and the peak of dobutamine dose (p> 0.05), but there were a significant increase in ICM patients when using low dose of dobutamine (p =0.016). Conclusion: PWTD echocardiographic methods and Long-axis dobutamine stress M-mode are quantifiable, noninvasive and reproducible techniques for segregation bettwen ischemic and non-ischemic cardiomyopathy so may be beneficial simple methods for typical dobutamine stress checking to disclose CAD cases in patients had dilated cardiomyopathy, chiefly in the presence of LBBB.