We assessed the left ventricular function in 24 patients with severe (forced expiratory volume in 1 sec < 50% of predicted) chronic obstructive pulmonary disease (COPD) and in 21 normal people. We measured the left ventricular systolic time intervals (STI) and echocardiographic left ventricular diameters, volumes, cardiac index, stroke volume index, echo ejection fraction and functional mean rate of circumferential fiber shortening (Vcf). In 13 of the 24 patients with COPD the mean pulmonary artery pressure and pulmonary artery wedge pressure were recorded. The STI in the patients with COPD were found abnormal while the echocardiographic parameters and pulmonary wedge pressure were normal. 1 patient had a high pulmonary arterial wedge pressure and a low Vcf. 2 patients had an ejection fraction < 60%, but in only 1 of these the Vcf was low. No patient had all three parameters abnormal. We conclude that in patients with COPD the increased right ventricular afterload and the interaction between left and right ventricles are responsible for the abnormal left ventricular STI, while the left ventricular function is normal.