Different chemicals can have genotoxic effects on the body, as confirmed by chromosome damage detection. Using conventional cytogenetic analysis and fluorescence in situ hybridization, we tested the extent of chromosome damage caused by the acetamiprid-based insecticide Mospilan 20SP on bovine peripheral blood lymphocytes at concentrations of, 2.5, 5, 25 and 50 µg.ml -1 after a 24 h incubation period. During the experiment, the presence of unstable aberrations-chromosomal and chromatid breaks and gaps-were detected by conventional cytogenetic analysis. With increasing insecticide concentrations, we observed a statistically significant increase in chromosome damage frequency after 24 hours of exposure. Fluorescence in situ hybridization was used to detect stable structural aberrations; whole-chromosome painting probes for bovine chromosomes 1 and 7 (BTA 1 and BTA 7) were used for this purpose. As a result of exposure to the insecticide, neither BTA 1/BTA 7 translocations nor other types of translocations were observed.