1. Seventy four days old White Leghorn male chicks of medium body weight, about 800 gr, was injected intramuscularly each other day with 0.1 mg and 0.5 mg of diethylstilbestrol (DES) for 15 days. The growth was promoted, in particular with 0.5 mg of DES injection. Weight of liver was increased, and adrenal weight tended to increase. 2. In liver, fatty acid and glycogen content was increased in DES, 0.5 mg, group. P distribution in liver was little affected, but RNA-P/DNA-P ratio was increased. Liver xanthine oxidase activity did not altered by the treatment. 3. In breast muscle, fat content was slightly increased. In serum, phospholipid was increased, but concentration of total N and residuol N was not altered. 4. Change of the above general components was weakened by the injection of 0.1 mg of DES. 5. Chicks of the same age, but lighter in body weight, about 670 gr,. were injected, similar to the above chicks, with 0.1 mg of DES and 0.2 mg of estrone. Their growth was depressed during the first 15 days, but was promoted remarkably in succeeding 35 days. The growth promotion for total 50 days was near upon the above heavier groups. Liver was enlarged in lesser degree, adrenal weight was not changed, and thyroid tended to slightly increase. 6. Noticeable change in general composition of the liver and muscle, and also in N and lipid content of the serum was not shown. P distribution and RNA-P/DNA--P ratio, xanthine oxidase activity, and vitamin A content of the liver were not changed noticeably. 7. It was shown that the effects of DES injection on the growth and liver components varied, depending on not only the age of chicks, but also on the degree of their development.