A cDNA (hSPO) encoding human salivary peroxidase (hSPO) was isolated and its nucleotide (nt) sequence determined. The coding sequence resembles those of other mammalian peroxidases and contains a 3' untranslated region of 538 nt. In a rabbit reticulocyte lysate transcription/translation system, the cDNA produces a major protein of approx. 67 kDa, which corresponds to the calculated molecular weight of unglycosylated hSPO.