It was determined if the sensitivity in macular mutant mouse to copper-induced toxicity was affected by sex or age. The sensitivity in 6-8-d-old or 3-4-wk-old macular mutant mouse to copper-induced toxicity was not affected by sex. However, 8-9-wk-old mutant females were more sensitive to copper-induced toxicity than mutant males. Furthermore, 6-8-d-old or 3-4-wk-old mutant males were more sensitive to copper-induced toxicity than 8-9-wk-old mutant males. However, age-related differences in sensitivity to copper-induced toxicity did not occur significantly in mutant females. On the other hand, in the case of normal mice, the sensitivity in 6-8-d-old or 3-4-wk-old mice to copper-induced toxicity was not also affected by sex. In contrast to mutant, however, 8-9-wk-old normal males were more sensitive to copper-induced toxicity than 8-9-wk-old normal females. Adult males were also more sensitive to copper-induced toxicity than 6-8-d-old or 3-4-wk-old males. However, age-related differences in sensitivity to copper-induced toxicity did not occur significantly in normal females. These results indicate that sex- and age-related differences in the copper-induced toxicity exist in macular mutant mice.