Effect of -gingerol, a major pungent component in ginger, on the proliferation of a rat ascites hepatoma AH109A cells was investigated by measuring [(3)H]thymidine incorporation into acid-insoluble fraction of the cultured cells and that on the invasion by co-culturing the hepatoma cells with rat mesentery-derived mesothelial cells. -Gingerol inhibited both the proliferation and invasion of hepatoma cells in a dose-dependent manner at concentrations of 6.25-200 muM (proliferation) and 50-200 muM (invasion). -Gingerol accumulated cells in S phase and elongated doubling time of hepatoma cells, and increased the rate of apoptosis. Hepatoma cells previously cultured with hypoxanthine (HX) and xanthine oxidase (XO) or with hydrogen peroxide showed increased invasive activities. -Gingerol suppressed the reactive oxygen species-potentiated invasive capacity by simultaneously treating AH109A cells with -gingerol, HX and XO or with -gingerol and hydrogen peroxide. Furthermore, -gingerol reduced the intracellular peroxide levels in AH109A cells. These results suggest that the suppression of hepatoma cell proliferation by -gingerol may be due to cell cycle arrest and apoptosis induction. They also suggest that the anti-oxidative property of -gingerol may be involved in its anti-invasive activity of hepatoma cells.