Although western medical treatment for heart failure has dramatically improved, limitation still exists where such treatment together with mechanical support fails to manage heart failure. It is unclear whether the addition of Kampo medicine to standard recommended therapy can improve clinical manifestations. To address this issue, we retrospectively evaluated the effects of Mokuboito used in 12 consecutive heart failure patients from April 2013 to April 2015 by analyzing endpoints such as symptoms, BNP concentration, and left ventricular ejection fraction (LVEF). Mokuboito significantly decreased plasma BNP concentration from 796.8 ± 830.8 to 215.6 ± 85.5 pg/ml (p < 0.01) and improved symptoms. There were no significant differences in other parameters including LVEF. In conclusion, the present study suggests that Mokuboito is a useful treatment on top of the standard heart failure medication in severe heart failure patients.