The effect of electrical stimulation of the cut cervical vagal nerves in dogs on airway resistance and circulating catecholamine concentrations was determined before and after propranolol. Airway resistance increased after 1 min of stimulation and decreased after 9 min of stimulation. The circulating catecholamine levels increased significantly in the pulmonary artery after 1 min of stimulation. After 9 min of stimulation the increase in the femoral artery was relatively more than in the pulmonary artery. This late increase most probably represents catecholamine supply from lung structures.