Previously, we have reported two major αarradrenergic receptor transcripts in rat brain of 3.8 and 3.0 kb and the cloning and characterization of the rat brain complementary DNA (cDNA) (RBα2c) specific for the 3.0-kb messenger RNA. In this report, we used rat brain cDNAs specific for the 3.0 and 3.8 kb transcripts, which encode the α2cand α2a-adrenergic receptors, respectively, and the RNGα2cDNA, which encodes for the nonglycosytated α2b-adrenergic receptor in rat, to study tissue-specific expression of the three α2-adrenergic receptor genes in rat To eliminate cross-hybridization of probes with transcripts from other α2genes, we subcloned fragments that encode for the highly divergent third cytoplasmic loop of each rat α2-adrenergic receptor cDNA and used RNase protection analysis to detect specific transcripts. We show that the three rat α2-adrenergic receptor genes have diverse patterns of tissue expression, and although transcripts specific for each α2-adrenergic receptor gene are found in brain and kidney, the levels of expression of each subtype differ in these tissues. We speculate on the significance of tissue-specific expression of the α2-adrenergic receptor genes.