Egypt has the highest prevalence rate of Hepatitis C virus (HCV) in the world, where, chronic hepatits C (CHC) is considered a major health problem. The standard treatment of CHC is combination therapy of pegylated interferon and ribavirin.  Successful treatment and sustained virological response (SVR) are only achieved in 30% of patients. Major adverse effects and high cost of the treatment makes predicting the treatment output is an important approach. The aim of this study to find an association between Vitamin D concentration with achieving SVR.  Patients and methods: In this study; 250 patients were selected and divided into 3 groups (100 CHC patients who achieved SVR, 100 CHC patients who did not achieve SVR, and 50 patients as control). Blood samples were collected to measure vitamin D concentration and routine liver function tests. Results: Vitamin D concentration was found significantly higher in the responders more than non responders. Conclusion: Vitamin D concentration is valid predector to the response of CHC patients to combination of pegylated interferon and ribvirin thrapy