A patient with the carcinoid syndrome had reversible airways obstruction as his predominant complaint. Standard provocation by intravenous adrenaline in conjunction with serial recordings of FEV1 provided a simple and reproducible method for testing the patient's response to a variety of pharmacological agents and food factors. The degree of the airways obstruction was increased by food with a high protein content, and lessened by alcohol. No protection against adrenaline-induced airways obstruction was afforded by a specific 5-HT antagonist (methysergide), a kallikrein inhibitor (aprotinin), adrenergic blocking agents or corticosteroids. Other pharmacological studies suggested that the airways obstruction was mediated by the secretion of histamine by the carcinoid tumour. Despite the deleterious effect of intravenous catecholamines, the patient derived considerable benefit from adrenaline or isoprenaline given by inhalation. The timing of administration in relationship to meals was important for maximal effect.