Thrombotic thrombocytopenic purpura (TTP) is a rare and often fatal disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, mental status changes, and renal dysfunction. Central diabetes insipidus (CDI) is a rare disease due to anatomic lesions of the hypothalamicpituitary system associated with various underlying diseases, or trauma. We present an unusual case of TTP and CDI in a 47 year-old African American female who was admitted to our hospital with crampy abdominal pain and nausea. The patient had tachycardia, fever and hypotension. The patient subsequently became confused, developed seizures, and her renal function deteriorated. Bone marrow analysis showed adequate megakaryocytes while a peripheral smear revealed severe thrombocytopenia, polychromasia and schistocytes. The diagnosis of thrombotic thrombocytopenic purpura (TTP) was made and plasmapharesis initiated. Over the next few days, the patient developed severe polyuria with a rise in serum sodium. Central diabetes insipidus was diagnosed and DDAVP (desmopressin acetate, 1-deamino-8-D-arginine vasopressin) was given. However, DDAVP was stopped several times due to worsening thrombocytopenia. Renal function worsened and the patient expired. A review of the literature revealed only one case of report of TTP and central diabetes insipidus. Our case was the only one reporting the use of DDAVP in such a setting.