ObjectiveTo evaluate clinical significance of direct antiglobulin testing(DAT) in anemia in patients with severe chronic hepatitis B(CHB).MethodsRed blood cell(RBC)related parameters detection and DAT were performed among 30 healthy persons, 30 CHB patients, and 50 severe CHB patients, clinical factors related to positive DAT were analyzed.ResultsRBC count, hemoglobin (Hb) concentration, and hematocrit（HCT）level in severe CHB patients were all lower than CHB patients and healthy group（P＜0.05）， RBC distribution width(RDW) in severe CHB patients were all higher than CHB patients and healthy group（P＜0.05）；the positive rate of DAT in patients with severe CHB, CHB, and healthy group were 62.82%, 13.33% and 0 respectively. RBC count, Hb concentration, and HCT level in severe CHB patients with positive DAT were all lower than severe CHB patients with negative DAT （all P＜0.05）, while RDW was higher than the latter (P=0.001); after RBC was separated through capillary, positive intensity of DAT of aged RBCs was higher than young RBCs in severe CHB patients （P<0.001）；among severe CHB patients, DATpositive and negative patients differed in gender, age, alanine aminotransferase, total bilirubin， complement C3,Creactive protein， and complication of diabetes(all P≤0.05).ConclusionAnemia in severe CHB patients may be related to immune hemolysis of aged RBCs induced by antibody adsorption.