We isolated a murine homeobox containing gene, Uncx4.1. The homeodomain sequence exhibits 88% identity to the unc-4 protein at the amino acid level. In situ hybridization analysis revealed that Uncx4.1 is expressed in the paraxial mesoderm, in the developing kidney, and central nervous system. The most intriguing expression domain is the somite, where it is confined to the caudal part of the newly formed somite and subsequently restricted to the caudal domain of the developing sclerotome. In the central nervous system, Uncx4.1 is detected in the developing spinal cord, hindbrain, mesencephalon, and telencephalon. The temporal and spatial expression pattern suggests that Uncx4.1 may play an important role in kidney development and in the differentiation of the sclerotome and the nervous system.