We have constructed recombinant baculoviruses containing cDNAs encoding either the α1− or the β1-subunit of the bovine GABAA receptor. In Spodoptera frugiperda (IPLB-Sf-21) cells infected with recombinant virus expressing either the α1− or β1-subunit, or in cells co-infected with both viruses, functional GABAA receptors were detected by whole-cell electrophysiological recordings. The threshold for the responses mediated by the homo-oligomeric channels (α- or β-) was 2–3 X 10-6 M GABA, and for the co-infected cells was 8 X 10-8 M GABA, suggesting that hetero-oligomeric channels formed in these cells. All GABA-induced currents were found to be inhibited by bicuculline and picrotoxin, potentiated by pentobarbital but were insensitive to benzodiazepines.