The beneficial effect of dopamine in circulatory shock induced by tricyclic antidepressants (TCA) overdose may be decreased due to compromise of the endogenous stores of norepinephrine caused by TCA. The successful outcome of two cases of TCA overdose complicated by hypotension, unresponsive to an initial treatment with physostigmine fluid challenge and dopamine (greater than 15 micrograms/kg/min) but subsequently responsive to an infusion of norepinephrine is reported.