Abstract: Gamma aminobutyric acid (GABA) is a potent inhibitory neurotransmitter that binds to hetero-oligomeric receptors in the mammalian brain. In a previous study, we documented specific GABA binding to isolated rat hepatocytes which resulted in inhibition of hepatocyte proliferation. The purpose of the present study was to define the nature of hepatic GABAA receptors and document their expression during rapid liver growth (post-partial hepatectomy). Polymerase chain reactions (PCR) with gene-specific primers derived from published sequences were performed with marathon-ready human and rat liver cDNA. Two GABAA receptor subunit types (&bgr;3 and &egr;) were expressed in the human liver and one (&bgr;3) in the rat liver. PCR amplification of the human GABAA receptor &bgr;3 subunit produced a single product (m.w. 53-59 kDa). In the case of the &egr; subunit, two PCR products were identified.