TPN [Tetrachloroisophthalonitrile], a kind of disinfectant, affected growth in Saccharomyces cerevisiae. Exposed to TPN under no lethal conditions, 70-, 90-kDa protein and hsp104 were induced. Each of them was not uniformly induced; namely, the 70-kDa protein was more sensitive to TPN among other proteins. Trehalose was also accumulated depending on the concentration. The degree of thermotolerance in yeast cells pretreated with 1.0 mg/l TPN was about 100-fold greater than in the control. Under this condition, TPN-inducible proteins were synthesized but trehalose was not accumulated. Although TPN-inducible proteins and trehalose were definitely synthesized with 10.0 or 100.0mg/l TPN treatment, thermotolerance was not acquired.