The rod dominated rodent retina is the preferred tissue for in vitro studies of mammalian retinal physiology and pharmacology. The rod pathway through the rat retina was investigated, therefore, in order to find out whether its organization follows the mammalian "plan." AII-amacrine cells of the rat retina were injected with Lucifer Yellow to characterize the morphology of this bistratified interneuron of the rod pathway. When sections or whole mounts of the rat retina were stained with antibodies against the calcium binding protein parvalbumin (PV), two different amacrine cell types were labeled: the AII-amacrine cell and a widefield amacrine cell. They occur at a ratio of 12:1. Weak label was also observed in ganglion cells. The density of PV-labeled AII-cells decreases from approximately 7,000 cells/mm2 in upper central retina to 2,000 cells/mm2 in peripheral retina. Their cell bodies form a regular mosaic, and the dendritic arbors of three neighbouring AII-amacrine cells overlap (coverage of 3).