Cadmium could induce the damage of endoplasmic reticulum. In the present study, we investigated the effect of Cadmium on messenger RNA expressions of endoplasmic reticulum resident selenoproteins, selenoprotein K, selenoprotein N, selenoprotein S, and selenoprotein T, in cultured chicken lymphocytes and the antagonistic effect of Selenium. Chicken splenic lymphocytes were treated with 10(-7) mol/L Selenium, 10(-6) mol/L Cadmium, and the mixture of 10(-6) mol/L Selenium and 10(-7) mol/L Cadmium in the culture medium for 12, 24, 36, and 48 h, respectively. Then, we detected the messenger RNA expressions of selenoprotein K, selenoprotein N, selenoprotein S, and selenoprotein T by using real-time polymerase chain reaction method. The results indicated that Selenium significantly increased the expressions of selenoprotein K, selenoprotein N, selenoprotein S, and selenoprotein T, which were reduced by Cadmium in chicken splenic lymphocytes. It indicated that endoplasmic reticulum was one target of Cadmium toxication, and Cadmium toxicity might be related to the reduced expressions of selenoprotein K, selenoprotein N, selenoprotein S, and selenoprotein T in chicken lymphocytes. Selenium reserved the protective role by increasing the expressions of selenoprotein K, selenoprotein N, selenoprotein S, and selenoprotein T. The present study provided a useful clue to investigate the possible pathogenesis of Cadmium toxicity.