The present study aimed to investigate the mutagenic effect of acriflavine and some plant growth hormones on mitochondrial DNA of Saccharomyces cerevisiae. Two yeast isolates isolated from different sources were used in this work. The results of acriflavine treatments showed significant toxicity on the viability of yeast cells via a dose – response appeared. This means that the survival of cells was decreased with the increasing in acriflavine concentrations. This is a clear evidence for the toxic action of acriflavine on yeast cells. At the concentration of 1 ppm the parent cells of isolate – A retain the normal respiratory abilities, while the isolate – B was less affected. The high rate of petite mutants appeared when the cells were exposed to 4 ppm. Isolate – B was more sensitive to acriflavine than isolate – A regarding the decline in the viability of cells and respiratory deficient mutants induced. In addition, kinetin and naphthyl acetic acid showed a dose – response for the viability of yeast cells without respiratory deficient mutants induced. This indicated that both plant growth hormones enhances the division of yeast cells leading the cells to continue growing. In addition, plant growth hormones plays several vital roles in biochemical processes related to cell cycle of yeast cells. The signaling molecules regulated cell growth must received significant attention because it is alarm sounds for the potential of carcinogenicity.