Cysteine sulfinic acid decarboxylase (CSD) is the rate-limiting enzyme for biosynthesis of taurine which is essential to biological processes such as development of the brain and eye, reproduction, osmoregulation as well as the anti-inflammatory activity of leukocytes. We report the cDNA sequence of murine CSD that predicts a polypeptide of 493 amino acids. This protein shares 98% and 90% of amino acids with rat and human CSD, respectively, indicating that it is a true ortholog of CSD. Northern blot analysis revealed that CSD mRNA is expressed in kidney and liver, and was not detected in lymphoid tissues and lung. The nucleotide sequence of murine CSD should be useful for genetic manipulation of the CSD gene.