Prefrontal repetitive transcranial magnetic stimulation (rTMS) has been shown to increase striatal dopaminergic activity. Here we investigated dopaminergic neurotransmission using single photon emission computed tomography (SPECT) and [(123)I]IBZM to indirectly assess the change in endogenous striatal dopamine concentration upon rTMS as compared with d-amphetamine challenge. SPECT imaging was performed twice each in five patients during rTMS, and in two patients who received 0.3 mg/kg D-amphetamine. Administration of rTMS led to a mean relative decrease in striatal IBZM binding by 9.6+/-6.2%, and d-amphetamine challenge (n=4) induced a mean relative reduction by 8+/-2.95% (difference not statistically significant). Acute rTMS challenge showed similar striatal dopaminergic effects to those associated with the administration of d-amphetamine, a substance known to increase synaptic dopamine.