Our double IHC staining kit utilizes an one step polymer-based technology. Primary antibodies of mouse and rabbit origins can be mixed and applied to tissue sections at the same time. The ready-to-use cocktail solution of polymer enzyme labeled goat anti-mouse and anti-rabbit secondary antibodies in the kit allows simultaneous demonstration of mouse and rabbit primary antibodies in blue and red colors on the sections. The double staining kit is simple, robust, and contains no biotin, therefore eliminating the biotin related background staining in the tissues.