DNA samples isolated from peripheral venous blood lymphocytes in 73 children with hydatid disease were studied. The polymorphism of exon 7 (A4889G) of the CYP1A1 gene was analyzed by polymerase chain reaction, followed by hydrolysis with restriction endonuclease HincII. The material for E. granulosus genotypes to be studied was obtained from the germinal layer of larvocysts. The fragment of the mitochondrial gene encoding for the first subunit of cytochome-C-oxidase was as a DNA marker. The amplified E. granulosus DNA fragments underwent direct sequencing and a genotype was identified. The findings have led to the conclusion that carriage of polymorphic allele Val of exon 7 (A4889G) of the CYP1A1 gene in those infested with E. granulosus genotype G1 (common, sheep strain) is a risk factor of the development of the clinical form of echinococcosis granulosus.