The antiviral effects of aqueous extracts of Terminalis chebula Retz., Sanguisorba officinalis L., Rubus coreanus Miq. and Rheum palmatum L. were examined by a cell culture system using a hepatitis B virus (HBV) producing cell line, HepG2 2.2.15. The extracts were assayed for the inhibition of HBV multiplication by measurement of HBV DNA and surface antigen (HBsAg) levels in the extracellular medium of HepG2 2.2.15 cells after an 8-day treatment. All extracts decreased the levels of extracellular HBV virion DNA at concentrations ranging from 64 to 128 microg/mL and inhibited the secretion of HBsAg dose dependently. Of the four tested plants, Terminalis chebula exhibited the most prominent anti-HBV activities.