Medical treatment for heart failure is still limited in patients with symptomatic aortic regurgitation (AR). Here we report the effects of mokuboito used in combination with standard medical therapy for heart failure in an inoperable patient with symptomatic severe AR. We observed acute effects of mokuboito in decreasing systemic vascular resistance and increasing cardiac output, as well as its chronic effects in improving New York Heart Association class, plasma brain natriuretic peptide levels, and left ventricular diastolic function. Given its efficacy, the use of mokuboito might be an additional treatment for patients with heart failure.