An anemia of juvenile chinook salmon (Oncorhynchus tshawytscha) is described and stages of development separated by recognizable syndromes. A vitamin E-deficient diet of low rancidity produced a severe microcytic anemia with strong immature red cell response and granulocytosis occurring 2 to 4 weeks before a drop in hemoglobin and hematocrit values. A vitamin E deficiency in association with diets of high rancidity produced a more severe anemia with impaired and delayed blood regeneration, microcytosis, abnormal red cell development, and a pronounced granulocyte response; complete recovery resulted when vitamin E was added to the diet.