Systemic acute phase response is a component of innate immunity and a consequence of local or systemic inflammation. A prominent feature of acute phase reaction is the alteration of gene expression in hepatocytes. The classical acute phase reactants are released into the blood and may be exuded into other body fluids. Generally, they exert antiinflammatory action and are important players of the homeostasis maintenance. The genetic background influences a persons response to disturbances of homeostasis, including infections, stress and tissue injury. The most frequent and physiologically relevant genetic polymorphisms of the representatives of classical acute phase proteins are discussed herein. The genetic variations of acute phase proteins or their regulators are associated with several pathological conditions. The highthroughput genomic and proteomic technologies combined with bioinformatics give the most recent approaches to the study and analysis of acute phase proteins, thereby widening the scope of the term ‘acute phase reactants’ or discovering novel ones. Simultaneous testing of numerous analytes, including acute phase proteins from the same, small volume sample may give diagnostic tools for diseases. Accumulating knowledge about acute phase reaction may lead to the development of novel therapies and other prevention alternatives.