Abstract Background: For Interleukin 28b Single nucleotide poly-morphism (SNP) rs8099917, the favourable T allele is asso-ciated with a higher SVR after PEG-IFN alpha/RBV therapy while the G allele is a risk factor for non-response. Aim of Study: To assess the value of Interleukin 28b (SNP) rs8099917 as a predictor of SVR. Patients and Methods: This study is a retrospective con-trolled study and was performed on a total number of 240 patients who were treated by PEG-IFN alpha/RBV for 48 weeks and (SNP) rs8099917 was done for the all patients. Results: TT genotype was more prevalent in SVR group than TG and GG genotypes. Conclusion: IL-28b single nucleotide polymorphism (SNP) rs8099917 is a strong pretreatment predictor of response to pegylated interferon and ribavirin therapy in egyptian patients chronically infected with HCV genotype 4.