We identified Saccharomyces cerevisiae mutants with 100% higher intracellular glutathione using 1-methyl-3-nitro-1-nitrosoguanidine mutagenesis. This method employs visual selection of the most pigmented colonies among met30 strains carrying ade1 and ade2 mutations. Since the method does not involve genetic engineering, the mutants are suitable for use in the food industry. (C) 2012, The Society for Biotechnology, Japan. All rights reserved.