Introduction The TGA CAT method has proved its usefulness for multiple purposes including diagnosis and management of bleeding disorders (1, 2), detecting hyper coagulability (3, 4), and monitoring and characterization of oral anticoagulant drugs (5, 6). Most of these studies are single-center studies and large prospective multi-center studies are needed to further validate the results. These multi-center studies have proved to be hard to produce due to lack of standardization of the method. In the last couple of years several articles have addressed the problem with large inter-laboratory variability for the TGA-CAT method by presenting thoroughly worked-out standardization protocols. Focus has been put both on the method itself and its pre-analytical factors as well as the usage of reference plasmas (RP) for normalization of results. One article showed that the choice of RP for the normalization of results could greatly reduce the inter-lab variability and that certain RP have a better ability to do so (7).