To explore the relationship between the perioperative change in erythrocytic pyruvate kinase (PK) activity and surgical hyperglycemia in the patients undergoing upper abdominal surgery under intravenous procaine balanced anesthesia. Seventeen patients with ASA grade Ⅰ～Ⅱ, being scheduled for selective cholecystectomy or subtotal gastrectomy, were randomly enrolled in our study. PK activity of erythrocytes and its pertinent modulators, such as adenosine triphosphate (ATP), adenosine diphosphate (ADP), inorganic phosphate (Pi), magnesium, plasma glucose and serum insulin were dynamically assayed in the surgical patients receiving intravenous procaine balanced anesthesia. The results showed that PK activity was decreased significantly at 10 min and 24 hours after operation as compared with that of preoperative period. Changes in PK activity were positively correlated with ATP/ADP ratio( r =0 680, P 0 05). It is our supposition that the decreased PK activity and the disturbance of glycolytic pathway might be directly or indirectly induced by anesthesia and surgical trauma, leading to hindrance of utilization of glucose and Pi, as well as synthesis of ATP. Therefore, an inhibition of glycolytic reaction is one of the important mechanisms of "surgical hyperglycemia".