Abstract: Objective  To investigate the relationship between extracellular fluid/intracellular fluid ratio (ECF/ICF) and geriatric nutritional risk index (GNRI) in the elderly, and to determine the predictive value of ECF/ICF combined with GNRI for all-cause mortality in maintenance hemodialysis (MHD) patients.   Methods The medical records of 486 MHD patients treated in Taizhou Central Hospital from October 2010 to October 2015 and subjected to routine biologic resistance (BIA) body composition examination were retrospectively analyzed. Their demographic and clinical data and ECF/ICF were retrieved from the medical records, and their GNRI was calculated by a basic formula. Based on the median of GNRI [94.53 (84.22, 99.17)] and the median of ECF/ICF [0.56(0.41, 0.87)], the patients were first divided into high GNRI (≥94.53) group and low GNRI (< median) group, high ECF/ICF group (≥0.56) group and low ECF/ICF (< median) group; four subgroups were further derived: G1, patients with high GNRI and low ECF/ICF; G2, patients with low GNRI and low ECF/ICF; G3, patients with high GNRI and high ECF/ICF; G4, patients with low GNRI and high ECF/ICF.  Results  Multivariate linear regression showed that ECF/ICF was independently correlated with GNRI (β=-0.247, P=0.001). The 7-year survival rates in G1, G2, G3 and G4 groups were 74.4%, 57.6%, 38.7% and 20.9%, respectively (Log rank: χ2=28.845, P<0.001). Multivariate COX proportional hazard regression showed that the adjusted HR for all-cause mortality in G2, G3 and G4 were 8.73 (95% CI 3.62～47.72), 16.27 (95% CI 6.42～64.33) and 20.32 (95% CI 11.38～73.26) respectively using G1 as a reference. After adding GNRI, ECF/ICF, and the combination of GNRI and ICF into the basic model, the C index of death risk model was improved from 0.714 to 0.743, 0.813, and 0.831.  Conclusions   ECF/ICF was independently correlated with GNRI, and both of which were the strong predictors for all-cause mortality in MHD patients. The combination of GNRI and ECF/ICF improved the ability to predict mortality outcomes. We therefore recommend that GNRI and ECF/ICF should be included in routine evaluation of MHD patients.