3,3' Diaminobenzidine (DAB) is a widely used chromogen for immunohistochemical staining and immunoblotting. In the presence of peroxidase enzyme, DAB produces a brown precipitate that is insoluble in alcohol. This product is available in a two component form consisting of a liquid, refrigerator stable DAB Chromogen and DAB Substrate. The standard working dilution is 40 ul (0.9mg) of DAB Chromogen per 1ml of DAB Substrate, although the ratio can be adjusted as desired. The use of liquid components reduces some risks associated with the handling of powders (i.e. dust inhalation) and eliminates waste that often results from using tablets that require a predetermined final volume. Once the two components are combined, the reagent can be used for up to six hours, making it ideal for automated stainers.