The aim of the study was evaluation of the effect of alpha-cypermethrin, deltamethrin or fenvalerate poisoning on hematological parameters in male and female Swiss mice in sub-acute poisoning. All pyrethroids examined, irrespective of the dose and sex of animals, caused an increase in the number of leukocytes in peripheral blood. In alpha-cypermethrin poisoning no changes in the hematological parameters were observed in male mice, whereas in female animals the administration of a lower alpha-cypermethrine dose resulted in an inhibition, and a higher dose in mobilization of hemopoietic system. In male mice poisoned with deltamethrin or fenvalerate, mobilization of the hemopoietic system was noted. No changes in the hematological parameters were observed in female mice poisoned with a higher deltamethrin dose. In female animals which were administered a lower deltamethrin dose or fenvalerate a decrease was noted in the number of erythrocytes, as well as hemoglobin and hematocrit levels.