Steady-state kinetic tracer analysis and two-dimensional chromatography and autoradiography were used to examine the relation of glucose transport to its metabolism in cultured chick embryo fibroblasts. Cytochalasin B was added to Rous sarcoma virus-infected cells to bring the rate of glucose uptake to the level of uninfected cells. It is concluded for chick cells in culture that: (1) the transport of glucose, rather than its phosphorylation, is the rate limiting step and (2) the difference in aerobic glycolysis between normal and virus-transformed cells at physiological glucose concentration may be a consequence of the difference in the rates of glucose uptake.