The ultrastructural localization of GABAA-receptor (GABAA-R) immunoreactivity (ir) in representative nuclei of the rat dorsal thalamus was investigated using the monoclonal antibody 62-3G1 to the beta 2 and beta 3 subunits of the GABAA-R [8]. The pattern of distribution and the subcellular localization of ir were similar in all the thalamic nuclei examined, with the exception of the reticular nucleus that was unlabeled. The reaction product was present along somatic and dendritic plasma membranes of thalamic neurons and on their intracellular membranes. No labelling was observed in glial cells. The ir was present in areas of plasma membranes related and non related to terminals containing flat vesicles, and also on invaginated plasma membranes suggesting a recycling process of the receptor complex. The distribution and mismatches between GABA neurotransmitter and its receptor localization are discussed.