The purpose of this investigation was to study the interaction between copper and dietary carbohydrates on clinical and enzymatic indices associated with copper deficiency. Copper deficiency was produced in rats by feeding diets adequate in all nutrients including selenium and chromium, but marginal in copper (1.2 micrograms/g diet) containing 62% of either starch, fructose, or glucose. During the fifth week, the fructose of the copper-deficient diet (20 rats) was replaced by either starch (10 rats) or by glucose (10 rats). The experiment was terminated after 11 weeks. Copper deficiency in rats fed fructose significantly lowered body weight and hematocrit, but increased liver weight, blood urea nitrogen, ammonia, cholesterol, and triglycerides when compared to rats fed starch or glucose. The copper metalloenzyme, superoxide dismutase, the selenoenzyme, glutathione peroxidase, and hepatic ATP were decreased in the copper-deficient rats fed fructose as compared to copper-deficient rats fed starch or glucose. These results indicate that fructose may be the dietary component which has a deleterious effect on copper and selenium status. Changing the type of dietary carbohydrate in copper-deficient rats from fructose to either starch or glucose ameliorated the severity of the deficiency. The protective effects were more pronounced with starch than with glucose.