N-[2-[4-(4-Chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide (PB12), a potent and selective dopamine D 4 receptor ligand, was used as a probe for the direct determination of the dopamine D 4 receptor density in rat striatum as an alternative to the subtraction method. The experiment was performed using [ 3 H]spiroperidol to label D 2 , D 3 and D 4 receptors and PB12 to determine directly dopamine D 4 receptor specific binding. The determined B m a x value was 82 fmol/mg protein. The contribution of the dopamine D 4 receptor to the overall population of D 2 -like receptors was 63%; however, this value cannot be considered reliable because of the observed difference in the kinetic profiles of D 2 , D 3 and D 4 receptors.