Rhodanese (thiosulfate sulfurtransferase) is expressed at high levels in liver and is involved in the detoxification of cyanide. The full-length cDNA corresponding to the mouse rhodanese gene (Tst), which is located on chromosome 15, was cloned by PCR amplification of a liver cDNA library and subjected to DNA sequencing. Alignment of the rhodanese cDNA sequences from mouse and rat, which we previously cloned (Biochem. J. 275:227-231), revealed 97.3 percent identity at the protein level and 94.6 percent identity at the DNA level. When the mouse and rat cDNAs were expressed under the control of IPTG-inducible promoters in E. coli, the cell extracts exhibited cyanide-metabolizing activity, indicating that both genes encode functional rhodanese molecules.