Since its introduction in 1979 protein blotting has become a routine tool in research laboratories. In the clinical laboratory its potential is becoming recognised for applications in fields such äs infectious and autoimmune diseases, allergy and others. In this article we would like to outline the basic principles of protein blotting, to illustrate these with soine examples related to clinical applications and to point out differences between these and classical methods.Immunoblot analysis: a new method for fingerprinting hospital pathogens Characterization of autoantigens and autoantibodies by immunoblotting Characterisation of allergens by protein blotting