Antibody clone H09 has been developed approx. 10 years ago at the German Cancer Research Center (DKFZ) in Heidelberg. Since it’s market release in 2010, clone H09 has established as a worldwide immunohistochemical goldstandard for glioma diagnosis, based on it’s unparalleled quality. In June 2015 a consensus and editorial meeting at the German Cancer Research Center (DKFZ), Heidelberg laid the foundation for the new WHO Classification of Tumors of the Central Nervous System. The 2016 CNS WHO classification presents a major restructuring and recommends IDH1 R132H immunohistochemistry (IHC) as an initial step in glioma diagnosis. Because of the high importance of clone H09, currently imitation products of the original anti-IDH1 R132H clone H09 are released but with lower quality and with distinct negative implications for application.