Abstract— Hexose uptake into synaptosomes has been shown to occur by a saturable mechanism with a relatively small component due to passive diffusion. Competition between glucose and deoxyglucose for entry was demonstrated and the kinetic properties of the process were studied by using glucose as a competitive inhibitor of deoxyglucose entry. During kinetic analysis of the transport process higher affinities for both hexoses were indicated by the results from the synaptosome preparation compared with those from cerebral cortex slices. The kinetic properties of glucose inhibition of deoxyglucose uptake into synaptosomes could not be interpreted completely in terms of a unimolecular transport model. The results appear to follow predictions for ‘doubly competitive inhibition’, and some evidence for polyvalency of the uptake process was obtained.