Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare clinical syndrome with a high mortality rate. There is no biomarker to predict the early therapeutic response. Objective: Our study explores the significance of serum ferritin in predicting the response of induction therapy. Methods: We retrospectively analyzed the clinical data of 102 adult patients with HLH admitted to our hospital. These patients received HLH-94 regimen for induction therapy. The patients were divided into remission group and non-remission group according to the response of induction therapy. Results: Ferritin values between 1-4 weeks post induction were predictive of remission (p<.05), which were higher in the non-remission group than in the remission group. Ferritin obtained 2 weeks post-induction had the highest ROC for predicting remission, with a cut-off value of 1188.5 mu g/L. And patients with ferritin lower than 1188.5 mu g/L had better response of induction therapy. Conclusion: Our study suggests that serum ferritin is a good indicator to predict the efficacy of induction therapy for adult HLH. KEY MESSAGES Serum ferritin is a good indicator for predicting the efficacy of adult HLH induction therapy. Serum ferritin two weeks after treatment may be a better indicator to judge the early curative effect. Serum ferritin after treatment also had a predictive significance for the survival of HLH.