The incidence of allele variants of glutathione-S transferase M1 xenobiotic detoxification gene and matrix metalloproteinase 9 gene was analyzed in patients with chronic obstructive pulmonary disease. A strict gene-gene interaction between these two genes in the formation of hereditary predisposition to this disease was first demonstrated. The combination of glutathione-S transferase M1 genotype 0/0 and matrix metalloproteinase 9 mutant allele (-15621) is a risk factor for chronic obstructive pulmonary disease (OR-7.7).