The stability of ceftriaxone sodium 100 mg/ml in the water for injection was tested at two temperature conditions (refrigerator and room temperature) and two storage containers (vitro and syringe). The stability of each sample was determined by high-performance liquid chromatography while storing for 5 days at room temperature and 27 days at refrigerator. The concentration of ceftriaxone sodium was 100 mg/ml which the hospital usually use as a filling preparation for I.V. push or Y-site injection. There was no significant difference between the storage in vials and syringes. There was no significant difference in the change of concentration until storing the reconstituted ceftriaxone sodium injection for 2 days at room temperature and 14 days at refrigerator. In conclusion, the ceftriaxone sodium 100 mg/ml in the water for injection can be stored in vial or syringe for 2 days at room temperature and 14 days at refrigerator after preparation.