Chicken ovalbumin upstream promoter transcription factors (COUP-TFs) are orphan members of the steroid/thyroid hormone receptor superfamily. COUP-TF homologues have been cloned in many species, from Drosophila to human. The protein sequences of COUP-TFs are highly homologous across species, suggesting functional conservation. Two COUP-TF genes have been cloned from human, and their genomic organizations have been characterized. To determine whether the genomic organization is conserved between human and mouse, we isolated two mouse COUP-TF genes (I and II) and characterized their genomic structures. Both genes have relatively simple structures that are similar to those of their human counterparts. In addition, we mapped mouse COUP-TF I to the distal region of chromosome 13 and COUP-TF II to the central region of chromosome 7. Furthermore, we mapped human COUP-TF I to 5q14 of chromosome 5 and COUP-TF II to 15q26 of chromosome 15. The results demonstrate that COUP-TF genes are located in chromosomal regions that are syntenic between mouse and human.