Thrombotic microangiopathic hemolytic anemias include thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS) and pregnancy associated thrombotic microangiopathy (TMA). Eight adult patients (four males and four females) with TMA who were treated between 2003 and 2004 at the Hospital Italiano de Buenos Aires were reviewed. The average age was 40. Clinical diagnosis of TMA was made on admission in four patients. During their stay in hospital, 4 patients developed HUS characteristics, three as TTP and one presented pregnancy associated TMA. All of them revealed thrombocytopenia and microangiophatic hemolytic anemia. Renal impairment was the third most frequent characteristic at presentation. The patients with TTP revealed the most severe condition. All patients received daily plasma exchange. Immunosuppressants were also used. Four patients recovered completely, 2 passed away, one remains with renal impairment and requires hemodialysis, and a colectomy was performed on one of them. The TMA syndromes are occlusive disorders associated to platelet microvascular thrombi. Systemic and renal circulations are primarily affected. TTP/HUS might represent an overlapping spectrum of idiopathic or secondary disease. Prompt recognition and treatment are vital, because high mortality occurs due to these disorders. Among the differential diagnosis of TMA we can refer to sepsis, neoplasms, systemic vasculitis, eclampsia and others. The mainstay treatments are daily plasma exchange and infusion with fresh frozen plasma. Improving the management of these diseases is required considering their high morbidity and mortality.