Coxsackievirus B(3)(CVB(3)) infection is the major cause of viral myocarditis, as well as dilated cardiomypathy. Rhubarb is one of the oldest and best-known traditional Chinese medicines. We initiated this study to determine the antiviral effect of an ethanol extract from the roots and rhizoma of Rheum palmatum (R. palmatum, one of the Chinese Rhubarbs), against CVB(3) in tissue culture cells and in a mouse model. The ethanol extract from R. palmatum showed significant inhibitory activity against CVB(3) on HEp-2 cells when added after infection, with IC(50) of 4 μg/ml, TI of 10. The medicated mouse serum still contained the pharmaceutical compound 24 h after intraperitoneal injection, and exhibited an antiviral effect on CVB(3)-infected cells, especially in the 0.3 and 0.5 g/kg/day treatment groups. Furthermore, the CVB(3)-infected mice were treated with the extract solution with dosages of 0.3 g/kg/day beginning 24 h post-CVB(3) exposures. The ethanol extract treated mice showed alleviated clinical signs, better survival rate, prolonged MTD and decreased viral titers compared to the virus control group. Our results indicate that the ethanol extract from R. palmatum has the anti-CVB(3) activity in vitro and in vivo and thus provides a re-evaluation of this old remedy with a broad therapeutic potential.