Three months old White Leghorn male chicks were injected subcutaneously near the neck with total 2 ml of synthetic estrogen sol, which contained 27 mg of diethylstilbestrol (DES), and 3 mg of euvestin, a derivative of DES, in 1 ml of aqueous suspension. In addition to the treatment with DES, both thiouracil (0.01% in the ration) and thyroprotein (0.01% in the ration) were fed for 9 weeks, and gain of the weight and effect on lipid metabolism in these three groups were compared with the control. 1. The hormone treatment caused growth stimulation, about 20%, in three injected groups. 2. The weight of anterior pituitary showed to reduce slightly in chicks fed thiouracil and thyroprotein with the hormone injection. Weight of the adrenal was little affected. Thyroidal weight showed no change in chicks of thyroprotein group compared with the control, but was increased in two other groups. Weight of comb and testis was remarkably reduced by the hormone treatment. The liver was enlarged. The abdominal adipose leaf developed markedly, most striking in the DES group, followed by the thyroprotein group, and the least in the thiouracil group, which was 6 times the weight of the control. 3. The liver fat content was increased in the order of DES, thiouracil, and thyroprotein group. The liver fat content in the DES group was 2 times of the control. In the leg muscle fat content was increased in the DES group, and no change was shown in the other groups. 4. A remarkable lipemia response w a s found with DES injection. Concentration of serum lipid reached to 5-8 %, contrasting with 0.4 % of the control group. Of the phospholipid, choline and ethanolamine-containing form was increased remarkably, and of cholesterol free form increased. The effect was the greatest in the thiouracil group. 5. Increase of liver lipid in each group treated with DES injection, was attributed to the increase of neutral fat. Of phospholipid, choline-containing form increased, and of cholesterol ester form increased. 6. On muscle lipid, neutral fat was slightly increased in the DES group, and change of lipid composition was little in two other groups compared with the control. 7. It was suggested that the thyrofunction stood in the secondary site for the increasing effect of fat deposition by the DES treatment.