Synaptosomal GABA uptake, sodium-dependent GABA binding to synaptic membranes and GABA receptor binding were measured in the cerebral cortex of five inbred strains of mice. These were the SWR/J, BALB/cJ, DBA/1J, C57BL/10J and C3HeB/FeJ strains. A highly significant negative correlation was found to exist between GABA uptake and blood pressure (r = ?0.92). A similarly good negative correlation occurred between sodium-dependent GABA binding and blood pressure. A poor correlation was observed between blood pressure and GABA receptor binding (r = ?0.46). Taken together with other evidence that exists in the literature, these results suggest that in mice blood pressure could be under the influence of the GABA system.