Calcium/calmodulin-dependent protein kinase II (kinase II) and protein phosphatase 2B (calcineurin) immunoreactivity in the rat hippocampus was studied 100 days after ischemic damage to hippocampal CA1 pyramidal neurons. One-hundred days after ischemia, only a few CA1 pyramidal neurons survived and they exhibited enhanced kinase II and calcineurin immunoreactivity in their basal and apical dendrites. The stratum lucidum of the CA3 (mossy fiber terminal area) had enhanced kinase II and calcineurin immunoreactivity. These results suggest activity-dependent regulation and redistribution of kinase II and calcineurin after intervention in neuronal circuitry.