The expression of nicotinic acetylcholine receptors (nAChR) in the rat superior cervical ganglion was investigated by Western blotting, immunohistochemistry and non-radioactive in situ hybridization applying probes for the α4-1 and β2 subunit mRNA. Immunoblot analysis of homogenized ganglia using the anti-nAChR antibody WF6 revealed a labeled protein band of apparent molecular weight of 40 kDa which is typical for the α subunit of nAChRs. Applying double-labeling immunofluorescence with antibodies against tyrosine hydroxylase, nAChR-like molecules were identified in most postganglionic neurons and in a subpopulation of small intensely fluorescent (SIF) cells. α4-1 and β2 subunit mRNAs were detected in all perikarya of postganglionic sympathetic neurons but not in SIF cells. These results suggest that antibodies raised against purified Torpedo AChR bind to nAChR in sympathetic ganglia and indicate that α4-1 and β2 subunits are constituents of nAChRs in sympathetic postganglionic neurons but not of SIF cells.