The contribution of trehalose and hsp104 to barotolerance in Saccharomyces cerevisiae has been investigated. Mutant strains, which lacked the ability to accumulate trehalose and/or hsp104, were examined for barotolerance and thermotolerance. All the mutants showed lower barotolerance and thermotolerance than their control strains. Trehalose had a greater protective effect towards high pressure than high temperature. Thus, trehalose and hsp104 are important factors for barotolerance and thermotolerance, but trehalose is more important for barotolerance than for thermotolerance.