Diacylglycerol kinase (DGK) is an enzyme that phosphorylates a second messenger diacylglycerol (DG) and is involved in a variety of pathophysiological cellular responses. We have previously reported that DGKζ may be involved in the selective vulnerability of hippocampal CA1 neurons in transient forebrain ischemia. In this study we aimed to further elucidate functional implications of DGK isozymes in the cerebral cortex suffering from infarction using a focal ischemic model. In the early phase of 90 min of middle cerebral artery occlusion, DGKζ-immunoreactivity is reduced rapidly in the nucleus of cortical neurons in the ischemic core, while DGKι and other neuronal proteins such as MAP-2 and NeuN remain intact. This suggests that rapid disappearance of DGKζ in ischemic neurons is a quite early event precedent to neuronal degeneration in response to ischemia. Furthermore, in the late inflammatory phase of infarction DGKζ-immunoreactivity is detected in non-neuronal cells including factor VIII-positive endothelial cells and ED-1-positive phagocytic cells. The present study suggests that DGKζ may play roles in various processes of ischemic brain damage including neuronal death and non-neuronal inflammatory response.