Calcium antagonists have been claimed to decrease the pulmonary artery pressure and increase oxygen uptake and cardiac output in patients with chronic obstructive pulmonary disease (COPD). This should tend to decrease the plasma levels of catecholamines. The purpose of the present study was to assess the effects of the vasodilating calcium antagonist, isradipine, on resting and exercise levels of catecholamines in patients with COPD. Eighteen patients with severe respiratory insufficiency (FEV1<1.01) were investigated. During maximum exercise, the baseline levels of plasma noradrenaline rose from 2.27 nmol/l (0.41-7.66: mean, range) to 3.86 nmol/l (1.3-12.2) (P = 0.0002) and plasma adrenaline rose from 0.39 nmol/l (0.07-1.02) to 0.64 nmol/l (0.07-1.77) (P = 0.0001). The patients were randomly allocated to receive either capsules of placebo or capsules of 5 mg of isradipine and were reinvestigated after 2 h and 3 months. There was no significant difference between the two groups concerning the change in plasma catecholamines, neither at rest nor at exhaustion. Furthermore, the increase in catecholamines during exercise in the two groups did not differ from each other, neither before administration of isradipine nor after. In conclusion, a vasodilating calcium antagonist did not alter the resting level or exercise induced increase in plasma catecholamines.