Atypical hemolytic uremic syndrome (aHUS) is a rare, lifethreatening, chronic, genetic disease of uncontrolled alternative pathway complement activation. The understanding of the pathophysiology and genetics of this disease has expanded over recent decades and promising new developments in the management of aHUS have emerged. Regardless of the cause of aHUS, with or without a demonstrated mutation or autoantibody, blockade of terminal complement activation through C5 is of high interest as a mechanism to ameliorate the disease. Eculizumab, an existing monoclonal antibody directed against C5 with high affinity, prevents the perpetuation of the downstream activation of the complement cascade and the damage caused by generation of the anaphylotoxin C5a and the membrane attack complex C5b-9, by blocking C5 cleavage. We report the successful use of eculizumab in a patient after kidney transplantation and discuss the disease aHUS.