We recently reported that differentiation of CD8+ T cells from the naïve to the effector state involves the upregulation of glucose-dependent metabolism. Glucose deprivation or inhibition of glycolysis by 2-deoxy-D-glucose (2-DG) selectively inhibited production of IFN-γ but not of IL-2. To determine a more global role of glucose metabolism on effector T-cell function, we performed gene array analysis on CD8+ effector T cells stimulated in the presence or absence of 2-DG. We observed that expression of only 10% of genes induced by TCR/CD28 signaling was inhibited by 2-DG. Among these were genes for key cytokines, cell cycle molecules, and cytotoxic granule proteins. Consistent with these results, production of IFN-γ and GM-CSF, cell cycle progression, upregulation of cyclin D2 protein, cytolytic activity, and upregulation of granzyme B protein and also conjugate formation were exquisitely glucose-dependent. In contrast to glucose, oxygen was little utilized by CD8+ effector T cells, and relative oxygen deprivation did not inhibit these CTL functional properties. Our results indicate a particularly critical role for glucose in regulating specific effector functions of CD8+ T cells and have implications for the maintenance of the effector phase of cellular immune responses in target tissue microenvironments such as a solid tumor.