Myeloperoxidase (MPO) is a peroxidase enzyme that in humans is most abundantly expressed in neutrophil granulocytes. In the presence of hydrogen peroxide and halides, MPO catalyzes the formation of reactive oxygen intermediates. MPO has been demonstrated to be a local mediator of tissue damage and the resulting inflammation in various inflammatory diseases, and may be important therapeutic target for the treatment of inflammatory conditions. Measurement of MPO in plasma may contribute to cardiovascular disease (CVD) risk stratification.