Summary A detailed description of reagents and technique of the FPT-test as fibrinogen assay method is presented. This simple but accurate test is very convenient for clinical routine use: results are quickly available and special laboratory equipment is not required. The performance of the assay on one drop of capillary blood offers advantages in pediatric care and states of shock, wherein intravenous punctures are cumbersom. The FPT-test is also useful in the presence of heparin (extracorporeal circulation, anticoagulant treatment) and in fibrinolytic states (spontaneous or inducted for thrombolytic trials). Ten different laboratories, testing the assay, have proven its reproducibility.