BACk gROUND: Paroxymal nocturnal hemoglobinuria is a rare non malignant clonal blood disorder that manifests with intravascular hemolytc anemia, bone marrow failure, hemoglobinuria and thrombosis.METHOD: This is a prospectvely designed study of the patent diagnosed PNH during the period of January 2008 to January 2009 in hematology unit of Natonal academy of medical science, Bir hospital. Clinical and laboratory features along with treatment response to anabolic steroid, cortcosteroids and cyclosporine were studied.RESULTS:  There were total of 12 PNH patents. To diagnose tweleve PNH patents in a single insttuton in a one year period is not very common. Ten (83.3%) patents were diagnosed by Hams test and two (16.7%) were diagnosed by analysis of CD 55 and CD 59 via fow cytometry. All were male patents. All patents presented with anemia.  Mean age at presentaton was 41.5 years of age. Mean hemoglobin was 6.27g/dl. Mean platelet count was 153000/ul. Mean WBC count was 4097/ul. Mean LDH was 2280U/L. Seven patents (58%) presented with hemoglobinuria.  Three Patents (25%) had hypocellular marrow. One patent (8.3%) had thrombotc episode. Two cases (16.6%) had splenomegaly. Five cases (41.6%) responded to the danazol. Similarly two cases (16.6%) responded to cyclosporine and rest (41.6%) responded to the cortcosteroid.  Eighty percent of patents with very severe anemia had hemoglobinuria. Eight patents (66%) had repeated episodes of hemoglobinuia during regular followup.CONCLUSION: Coomb’s negatve hemolytc anemia is the hall mark of PNH. High suspicion is needed to diagnose PNH. Most of the patents respond to cortcosteroid and anabolic steroid. While allogenic BMT is potentally curatve, the benefts must be weighted against the signifcant morbidity and mortality associated with the procedure. Recently Eculizimab is found to be very efectve in the treatment of PNH. Guidelines for management of PNH should be made in a country like ours where we don’t have bone marrow transplantaton facilites.Key words: clonal blood disorder, fow cytometry,  hemoglobinuria