Effect of in vivo administration of 0.5, 1 or 2 mg cadmium/kg body mass on peripheral blood polymorphonuclear leukocyte and splenic lymphocyte functional state and viability was examined in rats. Decreased proliferative capacity in vitro of splenic lymphocytes to T-cell mitogen concanavalin A was noted at all administered cadmium dosages. No changes in cell viability, except at the highest cadmium dose, were noted in lymphocyte cultures. Increase in some of the aspects of granulocyte function including spontaneous adhesion and activation was seen and was accompanied by increase in granulocyte survival ex vivo. Rise in cytokine inflammatory mediators which might influence lymphocyte and neutrophil functions was noted also. Differential effects of cadmium on these 2 cell types might be considered when studying in vivo cadmium toxicity.