After being pretreated with a sublethal dose of either oxidative or hyperosmotic stress, Saccharomyces cerevisiae cells could withstand a subsequent higher dose of the same stress. Cross-adaptation also existed between the two stresses. Especially wild-type cells pretreated with 1% KC1(a hyperosmotic stress generating agent) and hyperosmotic-resistance mutant cells could significantly resist to lethal concentration of H2O2 (10 mM). The addition of N-acetylcysteine (NAC) (30 mg 1(-1)) and MnSO4 (4 mM) showed a strong reversion to hyperosmotic stress, which implicated that antioxidants participated in yeast adaptation to hyperosmosis. The two sublethal dose of stresses treatment, especially hyperosmosis, increased the level of GSH, CAT, SOD and total antioxidant capability (T-AOC) in yeast cells, which indicated adaptation between oxidative and hyperosmotic stresses was accompanied by the production of above several antioxidants. Furthermore, at least seven new proteins were induced by both oxidative and osmotic treatment. (c) 2005 Elsevier Ltd. All rights reserved.