We aimed to investigate in detail the structural mutations after influence of actellic insecticide at different doses and different temperature conditions. We tested effects of single introduction of different doses of actellic: 48, 96, 192, and 384 mg/kg. Cytogenetic effect of actellic in bone marrow cells at different temperature regimens was studied. Following actellic administration, animals were being in two temperature regimes: normal (18-20°C) and high (37-38°C). After treatment with actellic, animals were kept within 1, 2, 4 and 8 hours at high temperature (37-38°C), i.e. in a thermostat (TV-80) with access of air. In experiments, the animals were divided into seven groups. The animals of the 1st group were administered actellic at a dose 384 mg/kg and kept under normal temperature until slaughtering. The animals of the 2nd group after administration of actellic were immediately placed in an environment with a temperature of 37-38°C. Animals of the 3rd, 4th, 5th, and 6th groups after treatment with actellic were transferred to conditions with high temperature, respectively, for 1, 2, 4 and 8 hours. The 7th group of mice was under normal temperature conditions without treatment with actellic. Our results have shown that in normal temperature conditions single exposure of actellic (384 mg/kg) did not affect the genetic apparatus of somatic cell, evidenced by the frequency of chromosome aberrations in bone marrow cells that were within the control levels. However, at high temperatures (37-38°C) the pesticide caused 6-fold larger number of chromosome aberrations in bone marrow cells, in comparison with normal conditions., Anvarjon Rakhmankulovich Shermuratov, and Literatura