Septal axons were visualized in the hippocampus by anterograde transport of Phaseolus vulgaris leucoagglutinin (PHAL) injected into the medial septal region, which contains large numbers of parvalbumin (PV)-immunoreactive somata. A proportion of the PHAL-labelled afferents in the hippocampus were shown to be immunoreactive for PV by immunostaining alternate sections. This population of septohippocampal axons alone was found to be immunoreactive for gamma-aminobutyric acid (GABA) following post-embedding immunogold staining of ultrathin sections cut from the same material.