Study design The study aims to evaluate the inter-laboratory variability of TGA-CAT performed TGT with a highly standardized protocol, how the use of RFs for normalization of data impact on variability of results and to evaluate the usefulness of TGA-CAT in monitoring prolonged FVIII drug administration. All Fluorometers of the participating center´s should be serviced and have temperature calibrated to 37 C prior start of the study. The latest software version must be installed (Thromboscope BV, Maastricht, The Netherlands, version V5.0.0.742). All laboratory equipment, pipettes, water baths, water purifiers, etc., needs to be calibrated. All plasmas, TGA-CAT reagents needed for the study will be administered and distributed to all participating centers by the Coagulation Unit, Malmö. An USB-memory stick containing a plate set-up scheme file and a video file covering critical pre-analytical and analytical steps will also be provided alongside the samples and reagents. Three pooled plasmas (normal, hypo- and hypercoaguable), three RF, five Adynovate and five Advate monitoring samples will be run five times on five different days by each participating center, following a scheme provided in the USB-memory stick, with two different triggers, PPP-reagent LOW (1 pM) and PPP-reagent (5 pM). Two test runs are scheduled each day to maximize RF and reagent usage. The reason for testing three different types of RF is the fact an earlier study results implied a better reduction of variability when using, for an example a hypocoaguable RF to hypocoaguable plasmas (9).