Despite significant improvements in the prognosis of thrombotic thrombocytopenic purpura (TTP), long-term neuropsychological deficits are frequent but probably under-recognised. Regular assessment of cognitive impairment using screening tools is therefore recommended. In this case report we describe two patients with neuropsychological late effects severely affecting their work capacity and quality of life. These late effects were not diagnosed until neuropsychological testing. We conclude that screening tools may not be sufficient to capture neuropsychological late effects in TTP.