Weanling rats were used in 4 experiments to determine the effect of Zn and Fe added to the diet alone and in combination in preventing Cd toxicity. Cd added to the diet at a level of 100 ppm depressed weight gain and blood hemoglobin in all 4 experiments. Supplemental Fe at 300 ppm in the diet offset the effect of Cd on weight gain and hemoglobin. Liver Cu was reduced and liver Zn was increased by Cd. Liver Fe was reduced by Cd at 100 ppm dietary Fe but not at 400 ppm. Depression of weight gain by Cd in one experiment was prevented by 68 ppm of Fe and 200 ppm of Zn added to a low Fe-low Zn diet, but not when either was added singly. Weight gain and hemoglobin of rats fed Cd were increased when rats were kept in galvanized cages as compared to stainless steel cages in one of two experiments. A Cd X Fe X Zn interaction appears to exist in the growing rat and environmental contamination with Zn is an important factor in determining the response to variable dietary Cd and Fe levels.