Primary and secondary antibodies, conjugates and the various detection systems must be prepared and diluted in appropriate solution systems before they can be applied in immunohistology. Phosphate buffered saline and Tris buffered saline are the most often used media. Optionally, these can be supplemented with blocking and stabilizing molecules such as bovine serum albumin (BSA) in order to prevent background reactions. The best formulations for dilution of antibodies and detecting reagents (f.e. labeled secondary antibodies, avidin/Streptavidin-biotin reagents) will depend on the material under study, and this has to be selected by trial. Some possible solutions are proposed.