Thrombotic thrombocytopenic purpura (TTP) is an uncommon multisystem disease characterized by microangiopathic hemolytic anemia, thrombocytopenic purpura, fluctuating neurologic dysfunctions, renal disease, and fever. Delayed diagnosis and treatment may lead to a high mortality rate that can be as great as 90%. We describe 7 patients in whom CNS involvement was the first clinical manifestation of TTP. Despite early diagnosis and treatment, 3 patients died because of multiple system organ failure. Four patients recovered completely. In patients with focal neurologic disorders in whom infectious CNS diseases were excluded TTP should be considered in the differential diagnosis.