The frequency and types of chromosome aberrations in peripheral blood lymphocytes were studied in 2 groups of healthy children of 15-17 yr old (55 persons) living in agricultural districts with a 3-fold difference in pesticide application. The average level of aberrant cells comprised 2.12% in experimental and 1.74% in the control zones, the difference between them being insignificant. In lymphocytes of people living in both districts, chromatid types of aberrations (especially single fragments) prevailed. The results obtained may serve as the base data for further investigation of the spontaneous mutagenesis of people living in these agricultural zones.