81 patients with confirmed HCV-infection and 48 healthy volunteers were examined. In healthy Caucasian participants living in Siberian region significant predominance of C/T genotype in promoter region C-590T of interleukin-4 (IL-4) gene and Q/Q and Ile/Val genotypes in points -50 and -576 of IL-4RA gene that codes alpha-chains of IL-4 receptor were revealed. In patients with HCV-infection predominance of C/T genotype in C-590T region in IL-4 gene (OR = 1.86), R/R genotype in Q-576R region of IL-4RA gene (OR=7.86), and Val/Val genotype in point Ile-50Val (OR = 2.6) of the same gene. Summary predictive coefficient of hepatitis C development in carriers of these genotypes approached to 95%. During analysis of role of allelic polymorphism of IL-4 genes in predisposition to hepatitis C development it is necessary to consider not only presence of allelic variants of promoter regions of the IL-4 genes, but also the polymorphism of genes coding molecules binding with this cytokine on target cells membranes and in its soluble form.