42 patients with chronic obstructive lung disease underwent right heart hemodynamics (Swan-Ganz catheter) and M mode echocardiography. Echocardiographic study showed that right ventricular index (RVI) and right ventricular anterior wall thickness (RVAWT) were increased in most patients, while septal thickness and motion were nearly always normal. The finding of impaired RVI and normal RVAWT in several patients, while no one showed normal RVI and increased RVAWT, suggests that arterial pulmonary hypertension results in initial dilatation and only later in hypertrophy of the right ventricle. Echocardiographic parameters were well correlated with hemodynamic and pulmonary function parameters. The good correlations between echocardiographic and hemodynamic data suggest that echocardiography may be a useful technique in the noninvasive assessment of the effects of pulmonary hypertension on the right heart in COLD.