Sterilization of prefilled syringe is mainly done by autoclaving or by ionizing radiation. Autoclave is not suitable of glass prefilled syringes and normal plastics, as there occurs a pH shift in glass syringes during autoclave sterilization process. Mainly used method of sterilization is ionizing radiations. Gamma sterilization has proved to be an efficient means of sterilizing prefilled syringes. Ionizing radiation has the advantage of sterilization the syringe plungers while they remain in their packaging. Possible risks of contamination are therefore limited to handling when transferring the components to the sterilizing zone where the products are packed. Radio sterilization takes place without moisture. Therefore, the stoppers do not have to be dried before use. Gamma rays are highly penetrating and can be used for treating whole syringe. The exposure dose is well controlled and can be easily recorde.