Host genetic factors may predict the outcome and treatment response in hepatitis C virus(HCV)infection.One of these factors is the single nucleotide polymorphisms of the interleukin 28B(IL28B)gene.We sought to evaluate the outcome of pegylated interferon and ribavirin therapy in association with IL-28B rs8099917 and rsl2980275 in patients infected with HCV genotype 4.A total of 180 patients with chronic hepatitis C were selected from Egyptians who have received combined therapy with pegylated interferon and ribavirin for 6 months and their response was evaluated after follow-up at 0,6,12,24 and 48 weeks from the beginning of the therapy.Blood samples were collected from responders and non-responders.Genomic DNA was extracted from whole blood and genotyping was carried out by polymerase chain reaction and restriction fragment length polymorphism(PCR-RFLP).Our results showed that TT genotype of rs8099917 was associated with higher sustained viral response(SVR)rates and G allele represented a risk factor for failure of response(OR=3.7,CI=1.8:7.64)while rs12980275 was not significantly associated with SVR in genotype 4 Egyptian patients.The determination of 1L-28B SNPs may be useful in enhancing correct prediction of SVR achievement in treating this group of genotype 4 patients. Host genetic factors may predict the outcome and treatment response in hepatitis C virus (HCV) infection. One of the factors is the single nucleotide polymorphisms of the interleukin 28B (IL28B) gene. We sought to evaluate the outcome of pegylated interferon and ribavirin therapy in association with IL-28B rs8099917 and rsl2980275 in patients infected with HCV genotype 4. A total of 180 patients with chronic hepatitis C were selected from Egyptians who have received combined therapy with pegylated interferon and ribavirin for 6 months and their response was evaluated after follow- up at 0, 6, 12, 24 and 48 weeks from the beginning of the therapy. Blood samples were collected from responders and non-responders. Genomic DNA was extracted from whole blood and genotyping was carried out by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) .Our results showed that TT genotype of rs8099917 was associated with ever-sustained viral response (SVR) rates and G allele represent ed a risk factor for failure of response (OR = 3.7, CI = 1.8: 7.64) while rs12980275 was not significantly associated with SVR in genotype 4 Egyptian patients. The determination of 1L-28B SNPs may be useful in enhancing correct prediction of SVR achievement in treating this group of genotype 4 patients.