FRETS-VWF73 is a very powerful Fluorescence-Quenching Substrate for the VWF cleaving protease ADAMTS-13. It is commonly used as a useful tool for the rapid measurement of ADAMTS-13 activity in plasma and is a predictive marker for various thrombotic diseases like TPP. Our new substrate FRETS-VWF73 can be easily used with a 96-well format in commercial plate readers.