The cDNA for rat NAD+-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH) was cloned from an intestinal cDNA library. The sequence of this cDNA was found to be identical to that of the reverse transcription-polymerase chain reaction (RT-PCR) product obtained using rat lung RNA as a template. The cDNA contains a 798-bp open reading frame that codes for a protein of 266 amino acids (M(r) 28,775) which shares 88.7% identity with the human 15-PGDH and 92.1% identity with the mouse 15-PGDH protein. The regions that are believed to be the NAD+ binding domain and the active site are conserved in the enzymes from the three different species. However, the sequence of the C-terminal 9 amino acids appears to be significantly different. The authenticity of the rat cDNA was confirmed by the expression of an enzymatically active 15-PGDH in E. coli.