Dihydropyrimidine dehydrogenase (DPD), the initial and rate-limiting enzyme in pyrimidine catabolism, has recently been purified to homogeneity from several species. In the present study the molecular cloning of DPD with isolation of a cDNA coding for bovine liver DPD is reported using polymerase chain reaction (PCR) methodology. Known amino acid sequence from purified bovine DPD was used to initially design mixed oligonucleotide primers for amplification of a cDNA fragment (65 base pairs). Specific primers were subsequently designed and utilized in the amplification of the full-length cDNA (4422 base pairs). Sequence analysis demonstrated a 74 nucleotide 5'-nontranslated region, an open reading frame of 3075 bases, and a 1273 nucleotide 3'-nontranslated region. Comparison of the nucleotide and deduced amino acid sequences of Bovine DPD to Pig and Human liver DPD reveals 93% and 92% identity respectively.