Decreased spontaneous cardiac baroreflex sensitivity (BRS), which could lead to the onset of cardiovascular events, has been demonstrated in chronic obstructive pulmonary disease patients. This study evaluates the effects of an exercise training programme on BRS. Twenty-one chronic obstructive pulmonary disease patients (mean+/-SD age 62+/-9 yrs; forced expiratory volume in one second 43.6+/-18.1% of the predicted value) with mild hypoxaemia (arterial oxygen tension 8.96+/-1.18 kPa) were compared to 18 healthy age-matched subjects. BRS was calculated as the slope of the baroreflex sequences between spontaneous changes in systolic blood pressure and subsequent consecutive relative risk deviation length, and was measured in the supine position and following head-up tilt for sympathetic stimulation. Pulmonary function test results and blood gas levels, measured only in patients, did not change after the training programme. Exercise training increased the maximal sustained workload (16.5%) and peak oxygen consumption (20.5%). Before training, BRS was lower in patients than in controls (2.7+/-1.5 versus 7.8+/-4.9 ms x mmHg(-1)) and tilting induced a smaller reduction in BRS (13 versus 34%). After training, BRS increased to 3.4+/-2.6 ms x mmHg(-1) in patients but remained lower than in controls. The response to the tilt test remained unchanged after training. It is concluded that, in chronic obstructive pulmonary disease patients, exercise training is associated with a gain in spontaneous baroreflex sensitivity, reflecting cardiovascular benefits.