Background: Peroxidase is one of the most widely used enzyme markers in the immunoassay systems. Because of the higher titre of labeled enzymes, diluted reagent has a tendency to start losing its activity after a few weeks, even at 4ºC. Peroxidase-conjugate diluent is specially designed to solve this problem. Labeled peroxidase when diluted in this diluent will not lose its activity. This diluent will stabilize the peroxidase conjugate and will increase its shelf life for several years when stored at 4ºC. This Peroxidase diluent/stabilizer contains immunologically inert protein to further stabilize the protein peroxidase conjugate.