Transforming growth factor beta 1 (TGF-beta 1) is reported to play an important role in the induction of liver cell apoptosis. In this report, we demonstrate that TGF-beta 1 induces apoptosis in a rat Morris hepatoma McA-RH8994 cell line and rat primary cultured hepatocytes at similar doses and in a similar manner. Using McA-RH8994 cells, we screened a number of chemical reagents, aqueous extracts of crude drugs, and herbal medicines for their inhibitory activities on TGF-beta 1-induced apoptosis. The results indicate that Artemisiae capillaris spica (ACS) and the ACS-containing herbal medicine Inchin-ko-to, which are used for treatment of various liver disorders, exhibited the most potent anti-apoptotic activity. Various chemicals that were reported as inhibitors of apoptosis in other experimental systems showed no evident activity. By contrast, two of nine ACS ingredients we tested, capillin and capillene, showed activity at concentrations of submicrogram per milliliter. The inhibitory effects of Inchin-ko-to, capillin and capillene were also confirmed on TGF-beta 1-induced apoptosis of rat primary cultured hepatocytes. Inhibition of undesired apoptosis induced by TGF-beta 1 is expected to be beneficial for the treatment of various inflammatory liver diseases. Our findings therefore suggest the possibility that therapeutic effects of Inchin-ko-to on liver diseases might be associated with its inhibitory activity on TGF-beta 1-induced liver cell apoptosis.