Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematologic disorder characterized by hemolytic anemia and associated with thrombophilia and bone marrow failure. Early and accurate diagnosis and classification of PNH is essential to optimize outcomes. However, the diagnosis of PNH may be delayed or missed for months or even years in practice, and only 25% of newly diagnosed patients receive any PNH-specific treatment. Moreover, up to 20% of patients treated with C5 inhibitors continue to experience clinically significant extravascular hemolysis, leading to residual anemia and its complications. Thus, several new and novel complement inhibitors have been developed and approved. In this activity, Dr. Carlos de Castro reviews the diagnostic criteria for PNH and best practices for the selection of optimal treatment regimens.