A 65-year-old female patient was admitted to our hospital with the symptoms of chest pain, dyspnea and fatigue. She had undergone a tooth extraction three months before. She took no medication. Echocardiography revealed pericardial effusion. The serum alanine aminotransferase (ALT) at presentation was 650 IU/L and aspartate aminotransferase (AST) was 600 IU/L. Hepatitis C virus (HCV) RNA level was 150,000 IU/ml. Genotype was 1b. Acute pericarditis was considered to be caused by acute HCV infection. The patient was followed without treatment. One month later, AST and ALT were found as 65 IU/L and 82 IU/L, respectively; there were symptoms of effort dyspnea and fatigue. Echocardiography showed minimal decrease in pericardial effusion compared to one month previously. HCV RNA level was again checked and found as 155,000 IU/ml. The patient was given pegylated interferon. One month later, the pericardial effusion and related symptoms had disappeared. The pegylated interferon treatment was sustained for 24 weeks and HCV-RNA was found negative at the 3rd and 6th months of the treatment and six months after the end of treatment. We conclude that pegylated interferon may be offered to patients with symptomatic acute HCV-related pericarditis.