Quantitative in vitro receptor autoradiography was used to examine the effect of acute scopolamine administration on specific binding to components of the N-methyl-D-aspartate (NMDA) receptor complex in four regions of mouse hippocampus. The binding of [3H]glycine to the strychnine-insensitive site was increased 1 h after administration of scopolamine hydrobromide (10 mg/kg) in the ventral dentate gyrus. The study suggests that rapid alterations in strychnine-insensitive glycine binding can occur in response to cholinergic perturbations. Moreover, these data suggest a delicate interaction between cholinergic and glutamatergic projections in the hippocampus.