Abstract: To investigate the effects of different zinc sources on Bcl-2, Bax, Caspase-3 mRNA expression, dexamethasone was used to make the apoptosis model of thymocytes. Zinc sulfate and zinc methionine was added to the medium at the level of 1 000 μmol/L, the percentage of apoptosis nuclei were determined by flow cytometric analysis, Bcl-2, Bax, Caspase-3 mRNA were measured by RT-PCR. The results showed that both ZnSO4 and Zn-Met can modulate apoptosis induced by dexamethasone, they inhibited apoptosis (P＜0.01) and decreased DNA ladder happening; no difference was shown of modulating apoptosis between the two kinds of zinc (P＞0.05). Both kinds of zinc could inhibit the upregulating of Bcl-2, Bax, Caspase-3 mRNA induced by dexamethasone (P＜0.01). Cell availability and Caspase-3 mRNA expression of cells cultured with Zn-Met were higher than those cultured with ZnSO4 (P＜0.05). The percentage of apoptosis nuclei， Bcl-2, Bax mRNA expression were similar within two groups (P＞0.05). We draw the conclusion that both kinds of zinc could modulate apoptosis of thymocytes induced by glucocorticoid; the mechanism may involve the regulating ability of zinc on genes expression, and the two forms of zinc may go different ways in the regulations.