The localization of PKC subspecies alpha, beta, gamma, epsilon and xi was studied immunocytochemically in the rabbit retina. Conventional, Ca2+-sensitive PKC subtypes alpha, beta, gamma were all localized in different neuronal populations. The xi-subspecies, which does not require Ca2+ for activation, was colocalized with PKC-alpha. PKC-epsilon, which is independent of Ca2+ and DAG, was colocalized with PKC-beta. Some populations of neurons, including cone bipolar cells, contained none of the PKC-subspecies studied. These results imply a cellular segregation of different signaling pathways in mammalian retina.