Background: Massive blood transfusion is common in surgery: trauma, complicated surgery, organ implantation. Stored blood contains much lactate, ammonia, products of metabolism. These products have negative effects on patient\u2019s metabolic function which may be a cause of death. Objective: To study the change of blood biochemical indexes in surgical patients with massive blood transfusion at Viet Duc hospital. Subjects and method: A prospective study was conducted in the adult patients who had emergency and operation at Viet Duc hospital, from December/2004 to August/2006. All of them were transfused over 3000 ml of blood within 24 hours (pre-operation, intra-operation and post-operation). Results: During the period of study, there were 70 surgical patients with massive blood transfusion: men were more than woman (64%) and the mean age: 38\xb117. The survival rate was significantly improved (57%). The average transfused blood per patient per 24 hours was 3995ml\xb11067ml. There was a decrease in the value of pH, acid-base and HCO3 (the average pH value 7.218\xb10.181, lowest value 6.7). The average value of pH and HCO3\xac was higher in the survival patients than died patients (p<0.05). The mean level of K+ was 3.8\xb10.96mml/l. The increase in the level of K+ had a positive association with the amount of transfused blood. The mean level of Ca++ \xac\xacdecreased under the normal level (0.98mml). Conclusion: It should monitor blood gas and electrolytes continuously in surgical patients with massive blood transfusion in order to identify disorders soon for timely treatment.