Occult hepatitis B virusinfection (OBI) is defined as the presence of HBV DNA in liver or serum of individuals who test negative for hepatitis B surface antigen (HBsAg).We aimed at determining the prevalence of OBI in patients chronically infected with HCV in Upper Egypt and to evaluate the possible impact of OBI on the progression of the liver disease. This study included 200 chronic HCV infected patients. HBV DNA was detected in the serum of 21 patients (10.5%) by nested PCR. 13 of them were positive for anti-HBc. HBV viral load ranged from 4.2-60.1 IU/ml. The percentage of cirrhotics was higher among OBI/HCV dual infection (52.4%) versus HCV mono infection (34.1%). Our study concluded that the prevalence of OBI among chronic HCV patients in Upper Egypt was 10.5%. OBI correlated with the severity of liver disease. Total anti-HBc cannot be used as a surrogate marker for detection of OBI.