Myeloperoxidase (MPO) plays an important role in the oxygen-dependent microbicidal mechanism of polymorphonuclear neutrophils. The purpose of our study was to investigate the therapeutic potency of human MPO preparations. This paper is to present our work on MPO purification and its identification. White blood cells, isolated freshly from normal donors, were lysed with cetyltrimethylammonium bromide to liberate myeloperoxidase. The purified MPO was obtained by 65% (NH4)2SO4 precipitation followed by separation over the Sephadex G150 column. These pure MPO preparations were green in color and had an A430/A280 nm of 0.68. The enzymatic activity was of 29.77 u/mg. The pure normal MPO was composed of a 59,000 MW peptide, a 13,500 MW peptide, and a 38,000 MW peptide when subjected to SDS-PAGE under reducing conditions. The study of the therapeutic effect of the pure MPO on mice with C. albicans infection is under way.