We examined the distribution and density of N-methyl-D-aspartate (NMDA) displaceable L-[3H]glutamate binding sites in human hippocampal samples obtained postmortem from Alzheimer's disease (AD) patients and from age-matched controls. Binding to NMDA receptors was stable for at least 72 h postmortem, and the pharmacological profile corresponded to that described using electrophysiology. NMDA receptors were concentrated in the terminal fields of major hippocampal pathways including the perforant path, Schaffer collaterals and the hippocampal output to the subiculum, all of which are proposed to use an excitatory amino acid transmitter. Little if any change in hippocampal receptor density was observed in AD patients compared to age-matched controls except in one case where major hippocampal cell loss occurred. The distribution of NMDA receptors did, however, correspond to the predilection for neuritic plaques and neurofibrillary tangles in hippocampal subfields.