Gliomas are the most common form of primary brain tumors with an overall incidence of about 4 – 5 per 105 persons. There is growing evidence for a widespread role of the neurotransmitter γ-aminobutyric acid (GABA) in the growth regulation of many cell types, including neuronal stem cells and perhaps tumor stem cells. Recently we showed that human brain tumors express GABA-A receptors subunits that are generally down-regulated in glioblastomas (Smits et al, 2012). We further showed that there was a correlation between GABA-A channel subunits and patient survival. Whether tumor cells that are equipped with functional GABA-A channels maintain proliferative activity upon in physiological concentrations of GABA may depend on which subtype of GABA-A channels are activated. We have now examined 8 glioblastoma derived cell-lines and examined which GABA-A subunits are expressed and then, selected one cell line to study in detail the functional and pharmacological properties of the GABA-A channels expressed. We used the method of RT-PCR for determining the subunits expressed, immunocytochemistry to identify cellular location of subunits and the whole-cell patch-clamp technique to record GABA-activated currents. Our results show that the eight different cell lines all express GABA-A receptor subunits but the type of subunits that are expressed varies. Cell line U3047 expressed α1, α2, α3, α5, β2, β3, δ, γ3 and θ GABA-A receptors subunits mRNAs and was selected for studies of properties of the GABA-A receptors expressed in glial/tumor cells. Immunocytochemistry demonstrated expression of the α3 and β3 proteins. GABA concentrations ranging from 1 to 1000 μM were applied to the cells and gave a half-maximal concentration of current activation (EC50) of 10 μM. The current response to 10 μM GABA was enhanced by 1 μM diazepam and 50 μM propofol, modulators of GABA-A channels. The currents were inhibited by the GABA-A channels antagonists SR-95531 (100 μM) and picrotoxin (100 μM). Our results show that the GABA-A receptors in the glioblastoma cell line U3047 are functional and respond to classical agonists and antagonists of GABA-A receptors. The profile of the subunits expressed is similar to what we reported in glioblastoma tumors from humans (Smits et al., 2012). We propose that the cell line can be used as a model system to study how GABA signaling affects tumor development.