To determin the practical level estrogen administration, 100 Demura lime cockerels of 5 weeks were used in this experiment and alloted. into 5 lots at complete random according to the level of estrogen injected. In order to study the effect of estrogen administrations on growth, dressing percentage and weight of organs in Demura male chicks, estrogen was administrated into breast muscle at the different levels of 5,000IU, 10,000IU, 15,000IU and 20,000IU for 35days. The results are summarized as follows: 1. Body weight at the end of experimental period in E₄ group was the most(10.78%) showing the significance with P$lt;0.01 and E₁ and E₂ group apparently lighter than control group statistical significance were P$lt;0.01 in body weight gain among the treatments used estrogen. 2. The weight of comb was significantly increased P$lt;0.01 in all treatments compared with the control. Testicle`s weights had no significant differences among treatments but in all treatments the weight of testicles compare with the control had decreased. 3. Liver weight showed significance with P$lt;0.01 among the groups. There was no significance among other groups except E₄ group. 4. There were no significant differences in the weight of heart and spleen. Weights of heart and spleen were slightly reduced by the hormone treatment. 5. In the weight of hypophsis, there was no difference in all tested groups. 6. Weight of gizzard showed the significance with P$lt;0.01 among the groups, and there was no significant differences among other groups except E₄ group. The weight of intestine was obviously increased P$lt;0.05 in all tested groups, and, its weight was increased in order of E₂ group, E₁ group, and E₄ group. 7. Dressing percentage showed the significance with P$lt;0.05 among the groups and were increased in order of E₂ group, E₃ group, E₁ group and E₄ group.