Ganglia of the nervus terminalis have been shown to contain luteinizing hormone-releasing hormone (LHRH) immunoreactive cells in several mammalian species. These cells are always accompanied by clusters of cells non-immunoreactive to antiserum to LHRH. Using immunocytochemical procedures, we found choline acetyltransferase (ChAT) and vasoactive intestinal polypeptide (VIP) present in cell bodies and in nerve processes throughout the peripheral, intracranial and central projections of the nervus terminalis. In addition, a dense plexus of substance P (SP) immunoreactive fibers was seen in the nasal mucosa surrounding the nasal glandular acini and blood vessels. A number of SP reactive fibers were traced with the olfactory nerves through the cribriform plate of the ethmoid bone and appeared to enter the brain in the area of the central roots of the nervus terminalis.