The dissection of the pathogenic mechanisms of the various forms of the hemolytic uremic syndrome (HUS) has paved the way for the design of specific efficacious treatments. Such mechanistic approach led to a revolution in the management of atypical HUS with the use of the first-in class C5 blocker, eculizumab. The availability of this anticomplement drug has also raised unsettled questions regarding the cost or burden and optimal duration of therapy and its use in secondary HUS. The efficacy of eculizumab in Shiga toxin producing Escherichia coli-associated HUS is not to date established and the results of ongoing prospective studies are eagerly awaited. Nevertheless, the emergence of anticomplement therapies (eculizumab and other drugs in development) has transformed our approach of HUS.