Antibodies to functional glutamate receptor subunits were utilized as probes to characterize glutamatergic receptors in human postmortem brain tissue. Crude membranes from rat, monkey, and various dissected human postmortem brain regions were fractionated by SDS-PAGE and electrotransferred to nitrocellulose. Using antisera raised against rat antigens for AMPA/kainate (GluR1-3) and kainate (GluR5) glutamate receptor subunits, we have been able to detect specific bands on Western blots in rat, monkey, and human postmortem brain tissue. These antisera recognized bands at approx 105 kDa for the GluR1-3 and 115 kDa for GluR5 in humans, monkeys, and rats. All of these glutamate receptor subtypes appear to be glycosylated. We observed varying levels of expression in the human brain areas examined, with the highest degree of expression in the hippocampus and temporal cortex for AMPA/kainate receptor subunits, and in the cortex and cerebellum for the kainate receptor subunits. In addition, considerable heterogeneity in expression was observed between protein, NCAM. Our studies indicate that glutamatergic receptor protein changes related to various human diseases states may be examined in human postmortem tissue by Western blotting techniques utilizing these antibodies raised to the rat protein.