The effect of 1′-acetoxychavicol acetate (ACA), an anticarcinogenic compound naturally obtained from rhizomes and seeds of South East Asia plants, on the intracellular concentration of glutathione and the activities of enzymes related to glutathione metabolism was studied in Ehrlich ascites tumor cells. We showed in a previous study that ACA induced apoptosis in tumor cells and the cell death was reversed by the addition of N-acetlycysteine or glutathione ethylester. Here we found that ACA caused a rapid decrease in glutathione level in less than 10 min after ACA exposure. At the time, glutathione reductase activity was significantly inhibited and gamma-glutamyl cysteine increased by ACA exposure. These results show that ACA caused the decrease in the intracellular GSH levels in Ehrlich ascites tumor cells, suggesting that ACA-induced decrease of the cellular GSH levels can lead to growth arrest of cancer and enhancement of the efficacy other anticancer drugs.