PNH is a progressive, disabling and life-threatening illness, with disease morbidity and mortality caused by underlying chronic hemolysis. The PNH pathology is due to a mutation in the phosphatidylinositol glycan-complementation class A (PIG-A) gene, resulting in a deficiency of glycosylphosphotidylinositol (GPI)-anchored proteins and the absence of complement inhibitors in all blood cell types. PNH may be diagnosed at any age (median: early to mid thirties) and affects both genders equally. Diagnosis is via the clinical presentation of intravascular hemolysis, as measured by lactate dehydrogenase (LDH), and evidence of GPI-deficient blood cells measured via flow cytometry. The consequences of PNH-associated hemolysis include manifestations such as thrombosis, renal failure, pulmonary arterial hypertension (PAH), abdominal pain, dyspnea, fatigue, anemia, dysphagia, hemoglobinuria and erectile dysfunction. The estimated post-diagnosis survival ranges from 10 - 25 years, with a 5-year mortality rate of 35%. Mortality causes include thrombosis (the leading cause of death), progressive end organ damage, renal failure, PAH and liver failure. To date, therapeutic management of PNH has been supportive care such as blood transfusions and anticoagulant therapy. However, the recent introduction of Soliris® (eculizumab) has offered an alternative treatment for patients with PNH. Soliris is a genetically-engineered humanized monoclonal antibody that specifically binds to the complement protein C5 and it is the first therapy to treat the chronic intravascular hemolysis central to PNH morbidity and mortality. Further details on the clinical impact of PNH-related chronic hemolysis will be discussed in this session, as will the evolving management approach of patients with this life-threatening disease. An additional presentation will highlight emerging data being generated from the experience using eculizumab in NTUH of PNH therapy and clinical presentation of PNH diagnosis by flow cytometry/FLAER.