BackgroundInterleukin-10 (IL-10) is an independent factor for predicting adverse outcomes in pediatric patients with hemophagocytic lymphohistiocytosis (HLH). However, little is known about its prognostic value in adult patients.MethodsThis single center retrospective study was conducted to explore the prognostic value of IL-10 in 101 adults newly diagnosed with HLH. The serum interleukin levels were quantitatively determined by chemiluminescence using cytokine profiling kits.ResultsSerum IL-10 levels were significantly increased in adult HLH patients. Elevated IL-10 levels was correlated with lower concentrations of hemoglobin (r = − 0.279, P = 0.005). IL-10 levels were significantly lower in patients with macrophage activation syndrome (MAS) than in those with infection-associated HLH (IAHS) and malignancy-associated HLH (MAHS) (P = 0.033, P = 0.012). Patients with MAS had relatively longer survival than those with IAHS and MAHS (P < 0.001). Univariate analysis indicated that hemoglobin < 8.2 g/dL, platelets < 40 × 109/L, lactate dehydrogenase ≥ 700 IU/L, albumin < 28 g/L, post-treatment ferritin > 1050 µg/L and IL-10 ≥ 129 pg/mL were poor prognostic factors for survival. However, multivariate analysis revealed that only high serum IL-10 levels (≥ 129 pg/mL) at diagnosis and high post-treatment ferritin levels (> 1050 µg/L) were independent risk factors for poor overall survival in adult HLH patients (HR: 4.087, 95% CI 2.064–8.090, P < 0.001; HR 3.814, 95% CI 2.042–7.126, P < 0.001, respectively).ConclusionsOur results suggest that higher serum IL-10 levels might be a prognostic marker in adult HLH patients.