The effects of Selenium (Se) on central dopaminergic function were examined in male Sprague-Dawley rats. In this experiment, animals were implanted with microdialysis probes and dialysates were analyzed for dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). After reaching baseline values, sodium selenite was either injected intraperitoneally (i.p.) or directly infused into the striatum (ST) or nucleus accumbens (NA). Se administration of 3.0 mg/kg (i.p.) significantly increased (70%) DA overflow in the ST. Meanwhile direct Se perfusion (10 mM) also caused a significant elevation of synaptic DA concentrations in the ST and NA. Levels of DOPAC and HVA were minimally affected in all studies. In order to test for the effects of DA receptor activation, animals were pretreated with quinpirole (0.5 mg/kg, s.c.), an hour prior to Se (10 mM) infusion through the probe. It was found that quinpirole pre-treatment reduced Se-induced changes in DA concentrations. It was concluded from the present study that Se's central action might be related to its ability to potentiate DA function.