Double-strand RNA dependent protein kinase (PKR) plays an important role in control of cell death. We previously reported that activation of PKR is associated with hippocampal neuronal loss in Alzheimer's disease (AD). Recent studies have reported that Parkinson's (PD) and Huntington's (HD) disease brains displayed progressive hippocampal neuronal loss in extrastriatal degeneration. However, association between PKR and hippocampal neuronal loss in PD and HD brains is not known. In this report, brain tissues from patients with PD and HD displayed strong induction of phosphorylated-PKR (p-PKR) in hippocampal neurons. Immunoblotting analysis also demonstrated that levels of nuclear p-PKR in the hippocampus affected by these diseases were increased compared with age-matched disease controls. These results suggest that a close association exists between PKR and extrastriatal degeneration in PD and HD pathology.