AIM To investigate the relationship between 25-hydroxyvitamin D(25-OHD) deficiency and hepatic encephalopathy(HE) in patients with chronic liver disease(CLD).METHODS A retrospective analysis of the results of 392 adult patients with chronic liver disease who were assessed for liver transplantation between 2006 and 2010 was undertaken. HE, severity of CLD, nutritional status and 25-OHD were analysed in patients assessed for liver transplantation between 2006 and 2010. Patients who presented with acute, fulminant or subacute disease, with a primary diagnosis of liver cancer, were assessed for re-transplantation or who did not have a 25-OHDmeasurement were excluded from the analysis. RESULTS One hundred and sixty-five patients were included in this analysis. The mean age of all patients was 53 ± 8 years. Moderate to severe 25-OHD deficiency was identified in 49 patients of whom 36 had grade 2-3 HE compared with 13 patients who were not encephalopathic(P ≤ 0.0001). Mild 25-OHD deficiency was not associated with HE. There was a significant correlation between the severity of 25-OHD deficiency and the severity of liver disease(r = 0.39, P ≤ 0.0001) and disease severity and the presence of HE(P ≤ 0.0001). Importantly, individuals with 25-OHD deficiency were more likely to have a diagnosis of overt HE(OHE) at a significantly lower model for end stage liver disease(MELD) score than individuals without OHE(P ≤ 0.0001). This significant difference was observed with MELD scores from 10 to 38.CONCLUSION25-OHD deficiency was observed in the majority of patients with CLD and for the first time was found to be significantly worse in patients with OHE. AIM To investigate the relationship between 25-hydroxyvitamin D (25-OHD) deficiency and hepatic encephalopathy (HE) in patients with chronic liver disease (CLD). METHODS A retrospective analysis of the results of 392 adult patients with chronic liver disease who were for liver transplantation between 2006 and 2010 was carried. HE, severity of CLD, nutritional status and 25-OHD were analyzed in patients assessed for liver transplantation between 2006 and 2010. Patients who presented with acute, fulminant or subacute disease, with a primary diagnosis of liver cancer, were assessed for re-transplantation or who did not have a 25-OHDmeasurement were excluded from the analysis. RESULTS One hundred and sixty-five patients were included in this analysis. The mean age of all patients was 53 ± 8 years Moderate to severe 25-OHD deficiency was identified in 49 patients of whom 36 had grade 2-3 HE compared with 13 patients who were not encephalopathic (P ≤ 0.0001). Mild 25-OHD deficienc There was a significant correlation between the severity of 25-OHD deficiency and the severity of liver disease (r = 0.39, P ≤ 0.0001) and disease severity and the presence of HE (P ≤ 0.0001). Importantly , individuals with 25-OHD deficiency were more likely to have a diagnosis of overt HE (OHE) at a significantly lower model for end stage liver disease (MELD) score than individuals without OHE (P ≤ 0.0001). This significant difference was observed with MELD scores from 10 to 38. CONCLUSION 25-OHD deficiency was observed in the majority of patients with CLD and for the first time was found to be significantly worse in patients with OHE.