The withdrawal of heterocyclic antidepressants and antipsychotic agents can produce nausea, emesis, anorexia, diarrhoea, rhinorrhoea, diaphoresis, myalgias, paraesthesias, anxiety, agitation, restlessness and insomnia. The withdrawal of monoamine oxidase (MAO) inhibitors may result in severe anxiety, agitation, pressured speech, sleeplessness or drowsiness, hallucinations, cognitive impairment, delirium, suicidality and delusions of persecution. The withdrawal of antipsychotic agents may give rise to symptoms preceding the onset of psychosis. These potential harbingers of relapse include anxiety, agitation, restlessness and insomnia. The withdrawal phenomena reviewed are usually prevented by gradually reducing the total daily dosage of the pertinent drug. Antimuscarinic agents often alleviate the distress produced by the withdrawal of tricyclic antidepressants and antipsychotic agents. MAO inhibitor withdrawal syndromes may constitute medical emergencies. The prevention of the evolution of a MAO inhibitor withdrawal—precipitated syndrome is a high priority.