A defect in cholinergic synaptic neurotransmission could explain the neuronal dysfunction that has been observed in rabies. The enzymatic activities of choline acetyltransferase (ChAT), acetylcholinesterase (AChE), and enolase were assessed in the brains of rabies virus strain CVS-infected and uninfected mice. No statistically significant differences in activities of ChAT, AChE, or enolase were observed in the cerebral cortex or hippocampus of moribund CVS-infected mice versus controls. Binding to muscarinic acetylcholine receptors, which was assessed with 3H-labelled quinuclidinyl benzylate (QNB), was also not significantly different in the cerebral cortex or hippocampus of CVS-infected mice and uninfected controls. The studies suggest that dysfunction of the cholinergic system is unlikely of fundamental importance in this mouse model of rabies.