A oral inotropic agent, denopamine(TA-064, (-)-alpha-(3,4-dimethoxyphenethyl aminomethyl)-4-hydroxybenzylalcohol), was shown to have strong positive inotropic effect in experimental animals. To determine effects of denopamine on the left ventricular9LV) function and clinical features in patients with severe chronic heart failure who were treated with conventional regimens, denopamine(5mg 3 times per day for 4 weeks) was administered orally to 28 patients with chronic heart failure(22 dilated cariomyopathy, 6 ischemic heart disease) and systolic time interval, 2-D and Doppler echocardiognaphy were performed to evaluate LV function. Denopamine had no effect on LV dimension, volume and fractional shortening, and produced modest increase of ejection fraction and cardiac index, and modest decrease of PEP/LVET and cardiothoracic ratio in the cheat X-ray(PA view). The stroke volume was significantly increased (32.8+/-10.0 to 36.4+/-11.1 ml, p<0.05). Systolic BP was decreased (131.3+/-32.7 to 123.2+/-20.8 mmHg, p<0.05) with little change in diastolic BP and heart rate. Subjective symptoms and NYHA functional class were improved (71.4%, 67.9%, respectively). No adverse effect and ECG abnormality were noted. In conclusion, the addition of denopamine to conventional therapy improved clinical symptoms and caused modest increase of LV contractile function in patients with severe chronic heart failure without significant untoward effects. Therefore, the addinion of denopamine to conventional therapy may be an effective and safe method for the treatment of chronic congestive heart failure.