Morning urinary norepinephrine (NE) was assessed in 36 patients suffering from panic and phobic disorders according to DSM III. Urinary NE excretion was significantly higher in this group than in a normal control one. Phobic patients excreted lower levels of NE than panic ones. No significant association was found between urinary NE levels and anxiety scores according to Zung's Anxiety Status Inventory or Wittenborn Psychiatric Rating Scale. The NE increase is interpreted as reflecting a sympathetic nervous system hyperactivity in anxiety. A concomitant effect upon NE metabolism of benzodiazepine withdrawal cannot be discarded since the group of patients previously medicated showed the highest NE excretion.