The authors describe a case of a 38-year-old male with minor stroke due to exacerbation of hereditary deficiency of ADAMTS 13 resulting in a chronic relapsing form of thrombotic thrombocytopenic purpura (TTP). The clue to the unusual pathogenesis was given by laboratory findings of a mild anaemia and thrombocytopenia. After two days of observation, the patient was treated with plasmapheresis resulting in normalized platelet levels and continued clinical improvement. Subsequent clinical and laboratory investigation verified the diagnosis and the patient was put on regular treatments with plasma substitution.