The effects of Mu-Fang-Ji-Tang (TJ-36), a traditional Chinese herbal medicine, were studied in a murine model of congestive heart failure induced by viral myocarditis. In the group of animals treated with Mu-Fang-Ji-Tang in a dose of 1.5g/kg/day, the heart weight to body weight ratio was significantly lower than in the control group (p<0.01). Histopathological grades were also significantly lower in the Mu-Fang-Ji-Tang treated group than in the placebo group (p<0.05). Furthermore, survival was increased in the Mu-Fang-Ji-Tang treated group, versus the control group (p<0.05). In vitro, murine J774A.1 macrophages inoculated with encephalomyocarditis virus produced a significantly greater amount of nitrites compared to non-activated macrophages. Mu-Fang-Ji-Tang added to the cells (25, 50, 75, 100 microg/ml) concomitantly with the encephalomyocarditis virus inhibited nitrite formation in a concentration-dependent manner. Mu-Fang-Ji-Tang showed a protective effect against myocardial injury leading to congestive heart failure in this animal model.