Abstract: Objective: To explore the relationship between the effect of DATS inducing apoptosisof MGC-803 cells and the intracellular level of reactive oxygen. Methods: Flow cytometry was used todetect the intracellular reactive oxygen species (ROS) level and the rate of apoptosis. Results: MGC-803 cells treated with DATS significantly increased in the intracellular ROS level and the percentage of apoptosis cell. Pretreatment of N-acetyl-l-cystein, a thiol-containing antioxidant effectively attenuates DATS-induced increasing of intracellular ROS and the consequent apoptotic of MGC803. Conclusion:These results suggest that the cellular generation of ROS plays a role in initiating DATS-mediated apoptosis of MGC-803 cells.