Mouse renal dipeptidase (mouseRDP, EC 3.4.13.11) was purified from the membrane fraction of kidney. The molecular mass of the enzyme was 115 kDa by size-exclusion HPLC and SDS-PAGE under non-reduced conditions and 58 kDa by SDS-PAGE under reduced conditions. The mouseRDP cDNA fragment was amplified from mouse kidney total RNA by reverse transcription-polymerase ŏffin reaction (RT-PCR). The mouseRDP cDNA was isolated from a kidney cDNA library using the probe. The primary structure of mouseRDP deduced from the cDNA showed a high homology with renal dipeptidase from various mammals, except for the amino-terminal and carboxy-terminal domains. Recombinant mouseRDP obtained from transfected mouse L929 cells containing the expression plasmids has the same Km value and molecular mass as native mouse renal dipeptidase. From Northern blotting analysis, expression of the mouseRDP gene was recognized in both kidney and liver.