Early electrocardiographic diagnosis of chronic cor pulmonale was attempted in the study of 312 patients with chronic pneumonia and in 251 normal individuals. In comparing the mean values of several ECG indices in chronic pneumonia, Stage 1, some signs with significant differences were revealed (amplitude of the PaVF wave, ratio of the hight of the PII and TII Waves, are of the PII wave). These signs appeared to be most informative. The following groups were singled out: 38 patients with chronic pneumonia, Stages 1 and 2 with signs of bronchospasm, and 53 persons with the same stages of the disease, but free of bronchial patency disorders. The ECG of these groups of patients was evaluated by means of the tables of electrocardiographic diagnosis of right atrial hypertrophy. The signs of overloading of the right atrium were revealed with statistical significance more often in patients with bronchospasm. The possibility of using this table for revealing early electrocardiographic signs of chronic cor pulmonale was also established; these signs include the amplitude of the PII wave greater than 2 mm and PaVF 1.5 mm, ratio of the hight of the PII and TII waves less than 0.75, the are of the PII wave greater than 0.09.