Weanling Wistar rats were given a low-iron diet (4-5 mg Fe/kg), a medium-iron diet (20 mg Fe/kg) or a control diet (40 mg Fe/kg) for 7 weeks. Pair-fed rats received the control diet in amounts equivalent to that consumed by animals on a low-Fe diet. Blood samples from the tail vein were taken after 4 weeks of diet and weekly during the following 3 weeks for determination of iron status parameters. Animals were weighed weekly. After 4 weeks of diet, the rats fed the 5 mg iron/kg diet were severely anemic and rats fed 20 mg iron/kg diet were moderately iron-deficient. Ad libitum and pair-fed controls had normal iron status. Total liver iron stores were lowest in anemic rats (p less than 0.001) and were also low in moderately iron-deficient animals (p less than 0.05). Growth rates decreased early in anemic and pair-fed rats. Both groups were smaller than controls and moderately iron-deficient rats after 2 weeks (p less than 0.05) and this continued until the end of the experiment (p less than 0.001). Body weights of pair-fed rats were lower than those of anemic rats from the 1st to the 3rd week of diet; thereafter, differences between the two groups were no longer significant.