Objective To evaluate hemolyticinfluence on 41 chemistry and immunology tests and define the hemolysis alert index, which can be used as evidence for sample rejection and test report verification.Methods Method evaluation.As a pair, both hemolyzed and non-hemolyzed serum samples were collected from the same patient at the same time.Hemolysis index and 41 tests were analyzed.The effect of hemolysis in different hemolysis level was evaluated by comparing results of the paired samples.The alertindex were defined by senior laboratory techniciansand clinical professionals based on discussion of widely accepted quality requirements.Results The number of sample with hemolysis index of 1,2,3 and 4was 24, 17, 7 and 4 respectively.Of the 41 analytes, 6 analytes increased in hemolyzed samples comparing to non-hemolyzed samples, namelyaspartate aminotransferase(AST), creatine kinase(CK), potassium(K),lactate dehydrogenase(LD),inorganic phosphorus(iP)and total bilirubin(TBil).Another 9 analytesdecreased in hemolyzed samples comparing to non-hemolyzed samples.These analytes are alkaline phosphatase(ALP), chloride(Cl), creatinine(Cr), immunoglobin M(IgM), sodium(Na), prealbumin (PA),rheumatoid factor(RF),triglyceride(TG),uric acid(UA).Hemolysis alert index was defined as 1 for AST,K,Na and LD;2 for Cr;3 for CK,iP,PA and TBil; and 4 for the other 32 tests.Conclusions Hemolysisalertindex were defined based on the investigation of hemolyticinfluence on 41 chemistry and immunology tests in ourlaboratory.However, hemolytic influence on clinical laboratory tests are closely related to the assay systems.So clinical laboratory should evaluate the hemolytic influence on its own analysis system,and define assay specific hemolysis alert index.