The results of the arterial blood study in 30 patients of cor pulmonale in acute exacerbation were reported.The study included gas analysis, and dominations of serum lactate,pyruvate, potassium,sodium and chlorine.All the items were determined simultaneously.The data demonstrated that when the arterial oxygen tension of the patients with cor pulmonale in acute exacerbation dropped below 60mmHg, the blood lactate concentration was most likely to show a rise, which was related not only to hypoxemia but also to alkalosis.Observations of the changes in concentration of blood lactate and pyruvate in some patients led us to believe that these changes were associated with the seriousness of the disease. Regular measurement of blood lactate and pyruvate concentrations might be helpful to judge the condition of the patient. Persistent rise in blood lactate concentraion suggested poor prognosis.