Abstract： Objective To investigate the effect of dobutamine stress test on left outflow tract gradients, left ventricular systolic and diastolic function as well as long axis function in patients with hypertrophic cardiomyopathy and ischemic heart disease. Methods Prespective analysis of 12 ECG and echocardiogram at rest and at peak stress in 21 patients with hypertrophic cardiomyopathy and 18 patients with isehemic heart disease was done. During dobutmine stress doppler echecardiography, heart rate and eft ventricular ejection and falling time were recorded. Long axis motion was derived from the M-Mode echocardiogram. Results Heart rate significant increased during dobutamine stress in three groups. Left ventrieular outflow tract gradient were detected in patients with hypertrophic eardiomyopathy, but not in ischemie cardiomyopathy group. Total ejection time per minute increased after dobu-tamine stress in both hypertrophic cardiomyopathy and ischemic heart disease groups (P < 0.01), Total filling time per minute did not significantly change after dobutamine stress in both hypertrophic cardiomyopathy and isehemic heart disease groups. Septal and lateral Long axis function decreased in both hypertrophic cardiomyopathy and ische-mic heart disease groups. Conclusion Total ejection time depends on heart rate response during dobutamine stress in patients with hypertrophic cardiomyopathy and ischemic heart disease. Long axis function decreases in in both hypertrophic cardiomyopathy and ischemic heart disease groups. LV geometric change may play an important role in hemedynamic changes in patients with hypertrophic cardiomyopathy and isehemic heart disease.