We report a patient of dilated cardiomyopathy (DCM) treated with metoprolol, a 硫1-selective sympathetic blocking agent, who showed marked improvement of cardiac function by serial echocardiographic study. For 4 years before the metoprolol therapy, we treated this 56-year-old man with salt restriction and constant dose of diuretics. He complained dyspnea or fatigue on mild exertion despite the treatment. Then he received incremental doses (5, 10, 20, 30, 40, 50, and 60 mg/day) of metoprolol. The administration of metoprolol decreased the heart rate (128 to 67/min.) and left ventricular (LV) diastolic dimension (62.4 to 54.4 mm), on the other hand, increased LV fractional shortening (6 to 20%) and LV ejection fraction (18 to 48%). In consequence, it markedly improved LV wall motion. His symptom became NYHA class II after this therapy. These results suggest that metoprolol can improve cardiac function of some DCM patients and that echocardiography is the useful method for the observation of serial changes of the therapeutic effect.