The mouse glucocorticoid-induced receptor (GIR) is an orphan G protein-coupled receptor highly expressed in brain and thymus (Harrigan et al., 1989; 1991). We have cloned the mouse GIR gene (Gpr83), determined its genomic organization and compared it with the human gene. The genomic organization of the gene is similar in both species although differences leading to specific splicing variants in the mouse have been found. Three introns interrupting the coding sequence are common to both mouse and human. A short sequence in the second intron of the mouse gene can be alternatively spliced in, leading to an insertion in the second intracellular loop of the receptor. This insertion constitutes an additional exon which is not present in the human genome. The human GIR polypeptide shares 89.5% and 91.5% identity with its mouse and dog orthologs respectively. Splice variants lacking the first extracellular loop and the third transmembrane domain have been found in human and mouse species. The receptor variants resulting from these minor transcripts are likely to be non functional. Comparative genetic mapping of the Gpr83 gene showed that it maps to regions of conserved synteny on mouse chromosome 9 (A2-3 region) and human chromosome 11 (q21 region).