In immune thrombotic thrombocytopenic purpura (iTTP), autoantibodies against the metalloprotease ADAMTS13 lead to catastrophic microvascular thrombosis. However, the potential benefits of recombinant human ADAMTS13 (rADAMTS13) in iTTP remain unknown. We report the clinical use of rADAMTS13 in iTTP. Administration of rADAMTS13 was associated with rapid suppression of disease activity and complete recovery in a critically ill patient whose condition had proven refractory to all available treatments. We show that rADAMTS13 causes immune complex formation, saturating the autoantibody and likely promoting its clearance. Our data support the role of rADAMTS13 as a novel adjunctive therapy in iTTP.