THE ciliary ganglion of the chicken contains only two types of neurons. Using monoclonal antibodies against the α and the β subunits of Ca2+calmodulin-stimulated protein kinase II (CaMPK-II) we found that the α-subunit was localized to the choroid neurons while β subunit was associated with the ciliary neurons. As both neurons receive their inputs from the oculomotor nerve, while their postganglionic axons leave via different nerves, the ciliary ganglion of the chicken is a neuronal system in which the functional differences between α and β CaMPK-II homopolymers in the regulation of synaptic transmission can be investigated.