Haemodynamic effects of a cold pressor test (foot immersion for 6 min in water at 5°C) without medication and after the non-selective 3-adrenoceptor blocker propranolol and the selective 3-adrenoceptor blocker metoprolol were studied in 17 volunteers. In the control study as well as in the study with the 8-adrenoceptor blockers cold exposure caused comparable changes, namely a blood pressure rise and a reduction of forearm blood flow. The increase in heart rate during cold exposure was clearly and equally reduced by both ,8-adrenoceptor blockers. Plasma noradrenaline rose significantly by 47%, plasma adrenaline did not change. It is concluded, that as to this kind of stress, ,81-selective-adrenoceptor blockade confers no important advantage over non-selective X3-adrenoceptor blockade.