The influence of the trichothecene mycotoxin T-2 on the mitochondria of Saccharomyces cerevisiae was studied. T-2 is a cytotoxic molecule inhibiting growth and macromolecular synthesis in S. cerevisiae. At low concentrations, T-2 toxin arrested yeast growth on glycerol medium and at higher concentrations, it arrested growth on glucose medium. The toxin was not capable itself of inducing petite mutations. Its inhibitory effect on the growth of petite strains, of both chromosomally isogenic and non-isogenic strains was less than that of grande strains. One exception to this was equally low susceptibility of psi+ SUP4-3 strain in both rho+ and rho- state. T-2 toxin was also capable of retarding the petite inducing activity of the mutagen, ethidium bromide. T-2 toxin inhibited the polymerization of P-ribo-sylaminoimidazole in an ade2 strain of S. cerevisiae. These results show that T-2 toxin is capable of interfering with the activity of the mitochondria in addition to its well studied effects on cytoplasmic protein synthesis.