The Mouse-&-Rabbit-on-Rodent Double Stain Polymer is specifically designed for a rapid double stain procedure of primary mouse and rabbit antibodies on mouse or rat tissue. This simultaneous double stain procedure can be done in approximately two hours, compared to approximately four hours for a sequential double stain. This single solution is a cocktail of conjugated goat anti-mouse horseradish peroxidase (HRP) polymer and conjugated goat anti-rabbit alkaline phosphatase (AP) polymer which reacts simultaneously with a cocktail of mouse and rabbit primary antibodies. The polymer technology is biotin-free and thus provides the elimination of endogenous biotin and reduction of IHC steps (no avidin-biotin blocking). This innovative cocktail of HRP- and AP-polymer technology provides a significant increase in staining sensitivity when compared to other conventional HRP or AP conjugated secondary antibodies. The double stain polymer detection can be used manually or on an automated stainer.