Anxiety is both an emotional state and a personality trait and may be either normal or pathological. The physiological changes of anxiety can be induced by sympathomimetic agents but the accompanying psychological changes may not be typical of anxiety. Conversely, the physiological concomitants can be attenuated using /3-adrenoceptor blocking agents although psychic anxiety may be only partly ameliorated. The central biochemical aspects of anxiety are poorly understood. Catecholamines rather than indoleamines appear to be involved in stress reactions. The locus coeruleus, a structure in the brain stem projecting widely to the cerebral cortex, has mainly adrenergic neurones and can be postulated to play a key role in the genesis of anxiety. In the treatment of anxious patients a combination of a central anxiolytic such as a benzodiazepine and a peripheral /3-blocker such as propranolol may be most efficacious.