The term 'thrombotic microangiopathy' (TMA) describes syndromes of microangiopathic hemolytic anemia, thrombocytopenia, and variable signs of organ impairment, due to platelet aggregation in the microcirculation. The term 'hemolytic uremic syndrome' (HUS) has entered clinical use to describe childhood cases of TMA dominated by renal impairment, while the term 'thrombotic thrombocytopenic purpura' (TTP) refers to adult cases of TMA with predominant neurological abnormalities. HUS and TTP show the same histological lesion characterized by widening of the subendothelial space and microvascular thrombosis and their different manifestations are secondary to the different distribution of the microvascular lesions. Available evidence orients towards endothelial injury as an important factor in the sequence of events leading to the microangiopathic process. Here we provide an overview of the pathophysiology, epidemiology, clinical manifestations, and management of TMA.