To study the effects of iron nutriture on tissue iron, copper and zinc contents, we fed iron-deficient or control diets to pregnant rats and their offspring. Pups were weaned to the same or opposite diet as that fed to their dams, yielding four groups: control-control (CC), control-deficient (CD), deficient-control (DC) and deficient-deficient (DD). Offspring were killed at 2, 21, 30, 60 and 90 days of age. Iron deficiency, induced by feeding a 5 ppm iron diet to the dam and/or to the weanlings, resulted in impaired body growth, lower hemoglobin and hematocrit levels and reduced iron levels in liver, spleen and kidney of the offspring. Two-day-old iron-deficient pups had hepatic copper levels 1.5- fold higher than control pups. By the end of the suckling period, hepatic copper levels in iron-deficient pups were 3-fold greater than those of control pups. Hepatic copper concentration in control-fed rats (CC and DC) declined with maturation. In deficient rats (CD and DD), this normal decrease in hepatic copper did not occur and in CD rats, there was a progressive accumulation of copper in the liver. Renal zinc concentrations were lower in CD and DD than in control-fed animals at 60 and 90 days of age. These interactions among iron, copper and zinc may assume clinical importance since iron deficiency is a common nutritional problem.