Long-term continuous pulmonary artery pressure monitoring was used to investigate pressure changes during different types of exercise and normal daily activities in patients with chronic heart failure. Nine men (mean age 55 years) with treated chronic heart failure underwent continuous pulmonary artery pressure measurement with use of a micromanometer-tipped catheter with in vivo calibration and frequency-modulated recording. The mean (+/- SD) maximal systolic pulmonary artery pressure (in mm Hg) was 59.4 +/- 26.1 on treadmill exercise, 54.9 +/- 30.6 on bicycle exercise, 52.5 +/- 26.1 walking up and down stairs and 43.5 +/- 23.9 walking on a flat surface. The mean maximal diastolic pressure (in mm Hg) was 27.8 +/- 14.6 on treadmill exercise, 25.5 +/- 14.9 on bicycle exercise, 24.9 +/- 14.8 walking up and down stairs and 20.4 +/- 12.5 walking on a flat surface. The increase in pulmonary artery pressure did not correlate with the severity of the limiting symptoms except during walking on a flat surface. All patients had marked postural changes in pressure, with the systolic pressure difference from lying to standing ranging from 8 to 25 mm Hg and the diastolic pressure difference ranging from 3 to 13 mm Hg. Eating meals caused an increase in pressure in three patients, but less than that when lying flat. There was an increase in pressure during urination in four patients equal to that when walking on a flat surface. None of these activities was associated with symptoms. Neither symptoms nor pulmonary artery pressure during maximal exercise is the same as during daily activities. This may restrict the value of maximal exercise tests in assessing patients with chronic heart failure.