Gene polymorphisms result from evolutionary processes representing mutations that survive in the population with a frequency higher than 1%. The most investigated type of gene polymorphisms are single nucleotide polymorphisms (SNPs). The SNPs of IL-12B (rs 3212227) A/C among a population of kidney graft CMV-seropositive recipients have an impact on a clinical events in cytomegalovirus (CMV) disease. Constitutive -308 G/A TNF-α polymorphism (rs1800629) is related to the susceptibility of HR-HPV-associated cervical dysplasia and cancer. SNP located 3 kb upstream of the IL- 28B gene (rs12979860) seems to be the strongest host genetic predictor of sustained virologic response (SVR) in hepatitis C genotype 1 patients. It is very important to identify viral and host genetic markers that may facilitate the risk of developing viral disease or some viral-associated cancers. In addition, these markers could be useful in the choice of effective treatments and preventive strategies against virally induced infection. [Projekat Ministarstva nauke Republike Srbije, br. 175073 i br. 175038]