AIM: Lack of liver enzymes normalization may discourage patients with chronic HCV from continuing therapy and may worry the clinician about treatment outcomes, raising the suspicion about the presence of concomitant causes of liver damage. The decision of discontinuing treatment solely on the basis of elevated liver enzymes in patients who are HCV-RNA-negative would result in a substantial proportion of patients not being cured of infection. We conducted this study to test the assumption that persistent liver enzymes elevation in patients with chronic HCV under pegylated interferon therapy who have achieved HCV clearance may be due to an underlying occult hepatitis B virus infection. METHODS: Seventy six chronic HCV patients under treatment with pegylated-interferon/ribavirin therapy were included. Group I (n=38); patients with persistent liver enzymes elevation despite therapy, while group II (n=38); patients with persistently non elevated liver enzymes. All patients were not viremic for HCV at the time of examination to hepatitis B virus. All patients were investigated for occult hepatitis B virus infection. RESULTS: HBV DNA was detected in 3 patients (3.9%), anti- HBc and anti-HBs were detected each in 14 patients (18.4%). None of the HBV markers showed statistical significance in relation to persistently elevated liver enzymes. CONCLUSIONS: Occult hepatitis B virus infection is not a cause of persistent elevation of