Abstract: Objective: To investigate the expression of CD16 on neutrophils in paroxysmal nocturnal hemoglobinuria (PNH) and evaluate its significance.Methods: The CD16 expression of peripheral blood neutrophils from forty healthy blood donors as control and thirty-six cases with PNH were measured by flow cytometry.The comparative study was carried on with CD55,CD59 and traditional Ham's test.Results: Compared with normal controls,the expressions of CD16,CD55 and CD59 in patients with PNH were deficient at different degrees,the difference was of statistical significance (P<0.01).Its accuracy was more high and specific than Ham's test.Conclusions: PNH is related with a deficiency of glycosylphosphatidylinositol-anchored proteins CD16.CD16 assay on peripheral blood neutrophils by flow cytometry is a sensitive and specific method for PNH diagnosis and it may have an important clinical significance for diagnosis of PNH patients.