The stable Cr(VI)-tolerant chr1-66T mutant of Schizosaccharomyces pombe, which carries one simple gene mutation responsible for Cr(VI) tolerance, accumulated and reduced the chromate anion (CrO(4)(2-)) significantly more slowly than did its parental strain 6chr(+). The mutant chr1-66T proved to be sensitive to oxidative stressors such as H(2)O(2), menadione, tert-butyl hydroperoxide and Cd(2+). Both the Cr(VI) tolerance and the oxidative stress sensitivity were attributed to a decreased specific glutathione reductase activity. These effects were also enhanced with a decrease in the specific mitochondrial Mn-SOD activity.