&NA;In this review, the physiologic and pharmacologic effects of tricyclic antidepressants are discussed as they apply to an overdose situation. Systemic arterial hypotension is a frequent occurrence in major overdoses. Occasionally conventional resuscitative measures such as crystalloid or colloid infusion are inadequate and vasoactive agents must be employed in an attempt to normalize blood pressure. The use of these agents is discussed in terms of their physiologic and pharmacologic actions in the management of refractory hypotension induced by tricyclics.(J Clin Psychopharmacol 1990;10:409‐413)