Abstract The retinal neurotransmitter dopamine (DA), elaborated from intrinsic dopaminergic neurons as amacrine and interplexiform cells, is known to modulate several complex functions mediated by D 1 and D 2 receptors in the vertebrate retina. In this paper, we characterized and localized DA receptors of the D 2 family on rod outer segments (ROS) of the rat retina by a radioimmunoligand binding assay and by immunohistochemistry. Anti-anti-DA conjugated antibodies (or anti-idiotypic antibodies Ab 2) with used as ligand; BSA-glutaraldehyde-conjugated spiperone, eticlopride (D 2 antagonists) and DA were used as displacers. The linear Scatchard transformation indicated that data were best fit to the one-site model. By using the peroxidase-antiperoxidase technique, an intense labeling was located on rods. These results supported the paracrine action of DA on the photoreceptor cell.