Twenty-four male subjects originally participated in a study to determine the effects of feeding diets comparatively low in copper (1.03 mg/day/2850 kcal) and containing either 20% fructose or starch on indices of copper status. During the course of feeding the diets for 11 wk, four of the subjects exhibited heart-related abnormalities and were removed from the study. Fructose ingestion had no effect on serum ceruloplasmin activity or serum copper concentration but did significantly reduce cuprozinc superoxide dismutase (SOD) activity of erythrocytes as compared to starch. Repletion of the subjects with 3 mg copper/day for 3 wk significantly increased SOD levels in subjects previously fed fructose but not starch. Apparent copper balance was significantly greater when the subjects consumed the fructose as compared to the starch diet. These results suggest that the type of dietary carbohydrate fed can differentially affect indices of copper status in humans.