Four-week-old chicks were fed on diets containing corticosterone (0, 5, 10, 20, and 40 mg/kg) for 9 days. Food intake, weight gain, plasma concentrations of corticosterone and other constituents, some organ weights, and adrenal cholesterol concentration were measured. Plasma corticosterone concentration was increased (P less than 0.05) by dietary corticosterone, particularly at the two highest rates of inclusion. The concentrations of glucose, cholesterol, triglyceride, protein, and uric acid in the plasma increased (P less than 0.05) with increasing concentrations of dietary corticosterone. Growth rate and relative weight of the cloacal bursa declined (P less than 0.05), while the relative weight of the liver increased (P less than 0.01), with increasing dietary corticosterone; relative weights of the spleen and adrenals were not significantly affected, nor was the adrenal concentration of cholesterol. Abdominal fat was increased sixfold by the two highest corticosterone concentrations.