BACKGROUND Patients with liver cirrhosis experience a large variety of metabolic disorders associated with more hepatic decompensation. Hepatic encephalopathy (HE) is a significant complication in liver cirrhosis patients, presenting a wide spectrum of neuropsychological symptoms. A deficiency of 25-hydroxy vitamin D (25-OHD) in the general population is associated with a loss of cognitive function, dementia, and Alzheimer's disease. Aim of the Study. Our study aims to check the relationship between low serum 25-OHD and HE in patients with HCV-related liver cirrhosis and assess its link with patient mortality. Patients and Methods. This study was observationally carried out on 100 patients with HCV-related liver cirrhosis. The patients were divided into 2 groups: Group A-included 50 HCV-related cirrhotic patients with HE, and Group B-included 50 HCV-related cirrhotic patients without HE. Assessment of disease severity using the end-stage liver disease (MELD) model and Child Turcotte Pugh (CTP) scores were done, and 25-OHD levels were measured. Comparison of vitamin D levels in different etiologies and different CTP categories was made using one-way ANOVA. Pearson's correlation between the level of vitamin D and other biomarkers was applied. RESULTS There was a statistically significant Vitamin D level difference between the two groups. A lower level of vitamin D was observed in the HE group where the severe deficiency was 16%, while it was 6% in the other group and the moderate deficiency was 24% in HE group as compared to 10% in the other group. The insufficient vitamin D level represented 46% of the non-HE group while none of the HE group falls in this category. Vitamin D level was statistically higher in Grade 1 HE than in Grade 2 which is higher than in Grades 3 to 4. Vitamin D level was also significantly higher in those who improved from HE as compared to those who died. CONCLUSIONS The lower levels of 25-OHD were associated with the higher incidence of HE in cirrhotic HCV patients. The worsening vitamin D deficiency was associated with increased severity of the liver disease, so vitamin D may be considered a prognostic factor for the severity of liver cirrhosis and high mortality rate in HE patients.