Huntington's disease is a hereditary neurodegenerative disorder characterized by involuntary choreiform movements and progressive dementia. Although controversy exists regarding the exact risk of suicide in patients with Huntington's chorea, the literature supports an increased risk of suicide, especially in the early stages of this disease. We describe a case of homicide-suicide involving a father and son. The 60-year-old father, the homicide victim, suffered from advanced Huntington's disease; his 30-year-old son, the assailant, had a history of depression but had not been diagnosed with Huntington's disease at the time of his suicide. The psychiatric implications of this dementing disease, including the risk of suicide, are discussed. The gross, histologic, and molecular genetic features of this neurodegenerative disease are also described. The recognition of this autosomal dominantly inherited disorder at autopsy can make a profound impact on the lives of surviving family members.