This experiment was carried out in order to study the transference of the radioactive materials into eggs of laying hens. Eggs were taken as the samples first at ¾ day after injection of seven radioisotope (^(85+89)Sr, ^(45)Ca, ^(24)Na, ^(32)P, ^(35)S, ^(131)I and ^(55+59)Fe) in dose of 80 μci. to the thigh muscle of laying hens of each experimental group respectively and then i day interval. They were devided into 3 parts: egg yolk, egg white and egg shell, and their feces were taken at the same. Uptake rate of the radioisotopes into the 3 parts of eggs and release rate in feces were investigated. The results obtained were as follows; 1. Uptake rates of the radioisotopes into the egg yolk were the lowest at ¾ day after injection and were the highest at different time (^(24)Na: 2 ¾ days, ^(45)Ca: 4 ¾ days, ^(32)P: 3 ¾ days, ^(85+89)Sr and ^(35)S: 5 ¾ days, ^(55+59)Fe: 6 ¾ days) and thereafter decreased gradually, showing the significance with P$lt;0.01 in process of time. 2. Uptake rates into the egg white were the highest in the early stages: ^(131)I at ¾ day, ^(35)S and ^(24)Na at 1 ¾ day, ^(45)Ca and ^(85+89)Sr at 2 ¾ days, ^(55+59)Fe and ^(32)P at 3 ¾ days, and then decreased significantly (P$lt;0.01). 3. Uptake rate of ss+seFe into the egg shell were the highest at 2 ¾ days and the others at ¾ day, and showed the decreasing significance with P$lt;0.01. 4. Release rates of ^(32)P and ^(55+59)Fe into the feces were the highest 1 ¾ day and the others at ¾ day, and then decreased significantly(P$lt;0.01) as the time elapses. 5. The transference rates of the radioisotopes into eggs of laying hens showed a tendency to be in direct proportion to their half life. The transference of ^(24)Na was insignificant about 6 days after injection and that of the others were ended about 10 days. The transference rate of ^(24)Na was high into the egg white and that of ^(55+59)Fe into the egg yolk only, being insignificant into the other parts.