Diagnosis of acute pulmonary embolism is difficult. The aim of the study was analysis of electrocardiographic (ECG) changes in patients with acute pulmonary embolism and analysis of correlations between electrocardiographic changes and pulmonary angiography and pulmonary artery pressure. ECG in 22 patients aged 47 +/- 13 years old (9 women and 13 men) with confirmed pulmonary embolism and without pre-existing cardiorespiratory diseases were analyzed. Most frequently tachycardia, negative T wave in III, aVF and precordial leads, dextrogyria and dextrogram in ECG were observed. In 20 patients 3 or more criteria were found. Index Milleri--an quantitative method of estimation of pulmonary embolism correlated with pulmonary artery pressure. Conclusion of this study is that ECG is one of the important diagnostic tests in patients with pulmonary embolism: it gives us information about changes in pulmonary arteries.