Thrombotic thrombocytopenic purpura is a relatively uncommon clinical syndrome characterized by thrombocytopenia, hemolytic anemia, and neurologic abnormalities. The case presented followed an infection with rubeola. The patient had a complete remission for 6 months. She manifested unusual skin lesions of the face which could have resulted from thromboses of the cutaneous vessels. Cr51 studies revealed a marked extracorpuscular type of hemolytic process as well as a moderate intracorpuscular hemolytic effect. The role that the phospholipid content of destroyed red cells and platelets have in causing the intravascular clotting in thrombotic thrombocytopenic purpura is discussed. Because of these suggestions further studies delineating changes in serum and/or plasma thromboplastic activity should be undertaken in this syndrome.