Objective To investigate the clinical features and prognostic factors of Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) in adults.Methods Clinical data of 40 adult patients with EBV-HLH admitted in the First Affiliated Hospital of Nanjing Medical University during January 2010 and September 2013 were retrospectively analyzed.The patients were divided into fatal group or survival group based on the results of 1-month follow-up.Logistic regression analysis was performed to identify risk factors of early death.Results EBV-HLH in clinic were characterized by fever,hepatosplenomegaly and lymphadenopathy.The incidences of peripheral blood cytopenias in 2 or 3 lines,hepatic dysfunction and hyperferritinemia in EBV-HLH patients were 60.0％ (24/40),95.0％ (38/40) and 94.9％ (37/39),respectively.Hemophagocytic phenomenon in bone marrow was observed in 83.8％ patients (31/37).Soluble CD25 (sCD25) was detected in 12 patients,and all were higher than 2 400 pg/mL.Nineteen patients died 1 month after fiual diagnosis with a fatality rate of 47.5％.Univariate logistic regression analysis indicated that EBV-DNA ＞ 105 copies/mL (OR =4.85,95％ CI:1.14-25.83,P ＜ 0.05),PLT ＜ 50 × 1012/L (OR =6.81,95 ％ CI:1.41-32.83,P ＜ 0.05),total bilirubin ＞ 50 μmol/L (OR =6.91,95％ CI:1.24-38.52,P ＜0.05),albumin ＜ 30 g/L (OR =7.50,95％ CI:1.80-31.28,P ＜ 0.01),serum ferritin ＞5 000 μg/L (OR =8.75,95％ CI:2.03-37.67,P ＜0.01) and polyserositis (OR =5.40,95％ CI:1.18-24.64,P ＜0.05) were risk factors of death within 1 month after final diagnosis,while chemotherapy was a protective factor of early death (OR =0.15,95％ CI:0.03-0.81,P ＜ 0.05).Conclusions EBV-HLH in adult has a poor prognosis.Significant elevated EBV-DNA,total bilirubin or serum ferritin,and notable decrease of peripheral blood platelet count or albumin level may indicate a poor prognosis,while chemotherapy may reduce the risk of early death.