The main purpose of this study was to examine the influence of pyrethroids, such as deltamethrin, cypermethrin and bifenthrin on the growth and the number of ρ-mutants in the cells of Saccharomyces cerevisiae yeast. SP-4 Mat alpha leu1 arg4 yeast strain was used as a standard strain for experiments. The cells were grown on a standard YPG liquid medium, under aerobic conditions until they reached the logarithmic or stationary phase of growth. Different concentrations of pyrethroid were added to the medium and the cells were incubated for 2 h. The survival rate of the cells was determined by diluting the cells and plating them on YPG Agar plates. The number of ρ-mutants was determined by examining the number of cells that hadn’t grown on YPG medium from among all surviving cells. As far as the investigated forms of pyrethroids are concerned, deltamethrin was the most toxic to yeast cells. It was also observed that low amounts of pyrethroid caused a greater destruction of cells at the logarithmic than at the stationary stage of growth. The influence of pyrethroid on the frequency of mutation of mitochondrial DNA of yeast cells was also studied. It was observed that after incubation with pyrethroid addition the frequency of ρ-mutation increased, especially at the logarithmic stage of growth.