Effect of Mercury chloride on the synthesis of NO2- and ATP were observed in EMT-6 cells which were culture with cytokines(IL-1alpha and IFN-gamma) and various concentrations of mercury chloride from 0.05 to 0.08 M. Viability of EMT-6 cells were observed above 90% in almost groups. There were not significant differences in the viability between mercury supplemented groups and control group. It suggests viability of EMT-6 cells were not influenced by these concentrations of mercury chloride. Results of the synthesis of nitrite showed significant time and group effect. There is a significant interaction effect between concentration of mercury chloride and culture time. The effect of various concentration of mercury chloride is not the same for all levels of culture time. There were significant differences in the synthesis of nitrite between mercury chloride supplemented groups and control group, and the synthesis of nitrite in EMT-6 cell by the supplement of mercury chloride was significantly decreased in a dose-dependent manner. Results of the synthesis of ATP showed a significant group effect, and the time main effect and the Group x Time interaction were also significant. There were significant differences in the synthesis of ATP between mercury chloride supplemented groups and control group, and the synthesis of ATP in EMT-6 cell by the supplement of mercury chloride was significantly decreased in a dose-dependent manner. These results suggest that the disorder of cell mediated immunity by mercury chloride could be related to the inhibition of nitric oxide synthesis which will be caused by the decreased synthesis of ATP.