α-Bungarotoxin (αBgt) was shown to inhibit the binding of the125I-labeled substance P (SP) and eledoisin (EL) to the rat brain membranes with K1values of 8.0±5.0 × 10-8and 1.1±0.5 × 10-6M, respectively. Lower inhibitory activity was manifested by several other postsynaptically acting snake venom neurotoxins. The αBgt inhibition of SP binding with a K1value of 8.5±5.5 × 10-8M to solubilized preparations of the rat brain membranes was demonstrated. The capacity to displace SP was found for d-tubocurarine and phencyclidine, although at concentrations considerably higher than those affecting the nicotinic acetylcholine receptors (AChRs). The results obtained suggest that some of the αBgt-binding polypeptides, distinct from neuronal AChRs, may be functionally associated with the tachykinin receptors (TchR). © 1989.