Using digital subtraction angiography, left ventricular function and pulmonary artery pressure at rest and during submaximal exercise (98 +/- 33 watts) were examined in 25 patients with systemic hypertension. All patients had normal coronary arteries and a normal left ventricular function at rest. Heart rate increased in all patients (from 82 +/- 14 to 134 +/- 20 min-1, p less than 0.001). Systolic blood pressure also increased significantly in all patients (from 153 +/- 12 to 190 +/- 14 mmHg, p less than 0.001). End-diastolic and end-systolic volumes did not change on average (89 +/- 22 and 87 +/- 19 ml/m2, 28 +/- 8 and 28 +/- 10 ml/m2, respectively), neither did stroke volume nor ejection fraction (61 +/- 18 and 59 +/- 16 ml/m2, 68 +/- 7 and 67 +/- 9%, respectively). The increase in end-systolic volumes and concomitantly the decrease in ejection fraction during exercise in 8 patients points to an impairment of left ventricular function. This effect is frequently found in ventricles with less distinct hypertrophy. Cardiac index increased in each patient (from 5.1 +/- 2.1 to 8.2 +/- 2.9 I/min/m2, p less than 0.001). This is caused by the increase in heart rate while stroke volume remains unchanged. Mean pulmonary artery pressure increased in all patients from 19 +/- 6 to 35 +/- 10 mmHg on average (p less than 0.001). A pathologic increase could be observed in 18 patients. There was no correlation to angiographic parameters of left ventricular function. The exercise test was stopped in 12 patients mainly because of dyspnea. In 11 of these patients a pathologic increase of mean pulmonary artery pressure was found. As in these patients the angiographic parameters of left ventricular function were normal, the increase in pulmonary pressure is related to an impairment of diastolic function caused by hypertrophy.