Ionizing radiation causes serious damage in a biological system. Some drugs and antioxidants are used to prevent such damage. In vitro we study the effect of free ascorbic acid(AA) and liposome encapsulation ascorbic acid (LEAA) to prevent damage induced by gamma irridiatin on rats blood . Liposomes prepared by thin film hydration method . Size ,and poly dispersed index (PDI) were analyzed by dynamic light scattering before and after encapsulation AA ,and shape was analyzed by transmission electron microscopy(TEM). Percentage encapsulation efficiency (EE%) of ascorbic acid was determined and IR study has been employed to reveal structure alteration in vesicles before and after encapsulation. two doses of free ascorbic acid ( 20 µg /ml ,40 µg /ml) were selected to be used for such purpose. Also the same doses were used encapsulated in liposomes . Our study were carried through UV-visible spectrum absorption spectrum , relative viscosity and conductivity measurement . The results show that EE% have a high encapsulation of vitamins C, there no detectable change is observed in size of liposome before and after encapsulation. The data obtained from UV-visible indicate that there is great change in the absorbance of sort band, and in the absorption A576/ A541 ratio in blood irradiated to 5 GY γ- irradiation by dose rate 62cGY/mint as compared with normal hemoglobin. The result indicated that ,the change decreases by increasing doses of free AA came close to normal hemoglobin and approaching more to normal in the case of liposome encapsulation ascorbic acid .