Distribution of interleukin-10 promoter-1082 G-->A single nucleotide polimorphism (SNP) in the group of cystic fibrosis (CF) patients has been studied. As a whole 42 CF patients and 73 persons of the control group were genotyped for IL-10 promoter-1082 G-->A SNP. The frequences of IL-10-1082 G-allele and GG high expression genotype increased significantly in CF patients in comparison to the control group. In addition, study of IL-10-1082 SNP distribution in the separate CF groups showed statistically significant increasing of the G-allele and GG-genotype frequencies in the subgroup of homozygous delF508 cariers. The possible role of IL-10 promoter SNP as a phenotype modifiers at different CF genotypes is examined.