Abstract
Background. It is known that many pesticides can act as mutagens by causing cytotoxic and negative genetic effects. Fipronil is insecticide, which widely used marketed under the trade names Adonis and Regent for locust control in Kazakhstan. Materials and methods. It studied mouse cells of internal organs (liver, lungs, spleen, testes) using the Comet assay and synaptonemal complex analysis in spermatocytes using immunocytochemistry methods. Results. It has been found that fipronil damages DNA in cells of the lung, spleen and liver intoxicated animals. Fipronil has a negative effect on the germ cells of mice, causing damage to synaptonemal complex structure of spermatocytes. Conclusion. The studies have shown that fipronil has genotoxotic effect.