Hepatitis C virus now affects more than 170 million patients worldwide and is a leading cause of chronic hepatitis, cirrhosis and hepatocellular carcinoma. The treatment of choice for chronic hepatitis C is the combination of interferon and ribavirin. Peginterferon has sustained absorption, slower rate of clearance and a longer half-life than unmodified interferon. Determination of hepatitis C virus genotypes is important for prediction of the clinical course and the outcome of antiviral therapy, and this study revealed that genotype 4 was the predominant type (86%) among the studied group of Egyptian patients with chronic hepatitis C. In this study, the parameters studied namely; age, weight, liver enzymes level, iron and ferritin and cholesterol levels, viral load, and quasispecies were of no significance as predictors of response to Peg-IFN combination therapy. This study revealed that females and genotype 4a patients respond more favourably to treatment. It also revealed that fibrosis score of the liver biopsy is a good pre-treatment predictor of unfavourable response to treatment. The number of quasispecies did not predict a response to IFN therapy, but it was significantly affected by it.