Young rats weighing 150 g (initial weight) were fed diets sufficient or deficient in vitamin A. Postweaning rats were used in order to retard the rapid onset of vitamin A deficiency. The effects of the deficiency were studied with respect to impairment of hematopoietic function and anemia. Values for hemoglobin and hematocrit provided evidence of anemia before the signs of severe vitamin A deficiency became apparent. These included alopecia, ocular lesions, and low levels of retinol in plasma and liver. At the point where liver stores of vitamin A were virtually depleted, however, estimates for serum iron, hematocrit, and hemoglobin were elevated to control levels. The latter phenomenon appeared to result from hemoconcentration. These data suggest that anemia may be a component of vitamin A deficiency, but might be masked by the dehydration that accompanies severe depletion of vitamin A.