As many as 52 families having patients with mucoviscidosis (2 : 100000 inhabitants) live in the Saratov region. The molecular and genetic examination was performed in 38 children. 52,6% of chromosomes in patients with mucoviscidosis carry the mutation del F508, 47,4% of chromosomes carry other mutations. 28,9% of them have homoxygotes, 47,4% have homozygomes by the mutation del F508, and 23,7% of patients with both rare or unknown mutations. The mixed mucoviscidosis form is revealed in 92,1% of children, the pulmonary one is revealed in 5,3% of children and the enteric one is revealed in 2,6% of children. It is shown that the incidence of mucoviscidosis corresponds to the assumed incidence for the European part of Russia: the level of chromosomes carrying the mutation del F508 is lower than in the countries of west Europe but higher than in the south of Europe and in the north-west of Russia.