Objectives: Comparision of the side effects due to interferon alpha 2a plus ribavirin and pegylated interferon alpha 2a plus ribavirin combinations for chronic hepatitis C infection. Patients and Methods: In this study, 36 patients, who received interferon alpha 2a, 3 million U, subcutaneously thrice weekly plus oral ribavirin 1000-1200 mg daily were compared with 49 patients, who received pegylated interferon alpha 2a 180 μgr, subcutaneously once weekly plus oral ribavirin 1000-1200 mg daily with respect to side effects. Results: Lack of appetite, headache and fatigue were more frequent in pegylated interferon alpha group, and these differences between groups were statistically significant (p<0.05). Conclusion: In our study the treatment is discontinued in two patients who received interferon plus ribavirin (anemia in one, both anemia and thrombocytopenia in the other) and three patients, who were treated with pegylated interferon plus ribavirin (anemia in one, both anemia and thrombocytopenia in one and psychiatric problems in the other). © Medical Journal of Trakya University. Published by Ekin Medical Publishing. All rights reserved.