A 15-year-old female patient with TTP was admitted to our hospital for further evaluation after the initial treatment with IVIG and prednisone failed. With the detection of anti-ADAMTS13 antibodies the acquired form of TTP could be diagnosed. Despite of therapeutic plasma exchange and high dose steroids no sustained remission could be achieved. However, application of rituximab led to a normalisation of platelet counts within one week allowing the termination of plasma exchanges and reduction of oral steroids. No side effects of rituximab were observed and the patient remained in clinical remission during the following months.