Abstract GABA A receptors were localized within laminar preparations of the rat distal colon myenteric plexus using a monoclonal antibody (mAb 62-3G1) to the affinity purified GABA A receptor/benzodiazepine receptor/Cl − channel complex. The immunofluorescence procedure showed that approximately half of the myenteric ganglion cells displayed extensive GABA A receptor labelling of their soma. This population was further characterised by treating some GABA A-receptor-labelled laminar preparations for the histochemical demonstration of nitric oxide (NO) synthase-related NADPH-dependent diaphorase activity. A subpopulation of the GABA A-receptor-immunoreactive cells (35%) were also found to display intense NO-synthase-related activity. These findings extend our understanding of the GABA A-receptor-related innervation of the rat gut wall herein referred to as ‘A-GABAergic’ and provides an anatomical basis for the pharmacologically-identified GABA-nitrergic pathway in the mammalian gut.