Hos3 is involved in cellular growth under osmotic stress in Schizosaccharomyces pombe. The recombinant plasmid pYFHos3 harboring the structural gene encoding Hos3 was constructed. The S. pombe cells harboring pYFHos3 contained the increased hos3 (+) mRNA content and exhibited an enhanced growth in high osmotic conditions, such as 1.5 M KCl and 2.5 M D-glucose, compared with the vector control cells. In the presence of hydrogen peroxide (H2O2), superoxide anion-generating menadione (MD) and nitric oxide (NO)-generating sodium nitroprusside (SNP), they could grow better than the vector control cells. In the presence of H2O2, MD and SNP and in the absence of a nitrogen source, the S. pombe cells harboring pYFHos3 contained less elevated NO and reactive oxygen species (ROS) levels than the vector control cells. Collectively, the S. pombe Hos3 also participate in the cellular defense against oxidative, nitrosative and nutritional stresses through down-regulating ROS and NO levels. 