This study was made to evaluate the effect of oral atenolol, a cardioselective beta-adrenergic blocking agent without intrinsic sympathomimetic activity, on left ventricular function in patient with essential hypertension. Atenolol, 100mg/day, was given to 11 hypertensive patients for 4 weeks, and its effects on arterial pressure, pulse rate, left ventricular dimensions and ejection phase indices of myocardial performance were examined by echocardiography. Echocardiographic studies were performed before treatment and after 4 weeks of atenolol therapy. Arterial pressure fell form 145/90 mmHg to 138/84mmHg after 4 weeks. Pulse rate fell significantly from 69/min to 58/min(p<0.05). Left ventricular end-diastolic and end-systolic dimensions and mean rate of circumferential fiber shortening(mVcf) did not change significantly. Ejection fraction increased significantly from 0.66 to 0.72(p=0.01). This results indicate that atenolol in the resting state has no depressant effect on left ventricular function in patients with essential hypertension.