The objective of this investigation is to determine mechanisms for regulation of retinal calmodulin kinase II (CaMKII). To this end, the expression and activity of CaMKII are examined in the retina of the rdta mouse, in which rod photoreceptors have been genetically ablated [47]. CaMKII levels are compared between rdta mice and the normal, littermate control mice. It is demonstrated that retinal CaMKII protein, enzyme activity and mRNA are significantly increased in response to the genetic ablation of rod photoreceptors. The data indicate that CaMKII expression/activity in amacrine and ganglion cells is negatively regulated by the rod photoreceptor-mediated visual input. The regulation appears to occur primarily at the transcriptional level. It is shown that the cytoplasmic polyadenylation element binding protein (CPEB), a regulatory factor for translation that is known to promote CaMKIIalpha translation in dendrites [83], is also present in the mouse retina. However, the polyadenylation-mediated translational control mechanism is not activated in this experimental paradigm.