The localisation and immunochemical identification of three different forms of calcium-independent protein kinase C (PKC-epsilon, PKC-delta and PKC-zeta) in retinas of different species were analysed by immunohistochemistry and SDS-PAGE/Western blotting, respectively. More than one component of different molecular weights reacted with the polyclonal antibodies in all retinal samples though in all instances a component of molecular weight corresponding to the individual PKCs was recognised and could be eliminated or reduced by preincubating the primary antibodies with the peptides used to generate the antibodies. PKC-zeta immunoreactivity was exclusively associated with the inner segments of the photoreceptors in both mammalian (guinea-pig, rabbit, rat) and non-mammalian (goldfish, chick) retinas. PKC-epsilon immunoreactivity is present in bipolar cells, particularly in their terminals of mammalian and goldfish retinas. In the chick retina immunoreactivity for this enzyme and for PKC-delta was with the inner segments of the photoreceptors. The Müller cells in mammalian retinas and a sub-population of ganglion cells in the goldfish retina exhibited positive immunoreactivity for PKC-delta. The immunoreactivities for all the PKC isoenzymes were eliminated or drastically reduced when the primary antibodies were first preincubated with the peptides used to generate the antibodies.