The antibodies against synthetic (183-192) fragments of β2- and β4-subunits of rat neuronal nicotinic acetylcholine receptor were used to study a β-subunit composition of nicotinic receptors in the inferior mesenteric ganglion of the guinea pig by both immunocytochemical staining and blocking of excitatory postsynaptic potentials induced by electric stimulation of the pre-ganglionic nerve (intermesenteric trunk). The β4-specific antibody stained 59.8±7.5% of neurons and inhibited the synaptic responses in all (n=10) neurons studied by 25.5±1.8%. The β2-specific antibody did not stain ganglionic neurons and did not affect the synaptic transmission. Taking into account the previously obtained data on the α-subunits found in this ganglion, it is concluded that the neurons of inferior mesenteric ganglion contain nicotinic receptors of α3(α5)β4 subtypes involved in synaptic transmission through the intermesenteric tract. © 2004 Elsevier Ireland Ltd. All rights reserved.