N-[1-(2-Benzo[b]thiophenyl)cyclohexyl]piperidine (BTCP) is a phencyclidine derivative highly selective for the dopamine (DA) uptake complex. Its effect on extracellular DA levels was studied by in vivo microdialysis on freely moving rats. In the striatum, BTCP induced a dose-dependent increase in DA levels, without affecting DA metabolites. In the nucleus accumbens, a lower increase in DA was observed, but with concomitant decreases in 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). These experiments show that the effects of BTCP on extracellular DA levels are significantly different on extrapyramidal and mesolimbic dopaminergic terminals.