Huntington's disease is a devastating disorder with no known cure. The disease results from an expanded sequence of CAG repeats in the huntingtin gene and leads to a movement disorder with associated cognitive and systemic deficits. Huntington's disease is diagnosed by genetic testing and disease progression can be followed with a variety of imaging modalities. The accumulation of aggregated huntingtin with associated striatal degeneration is evident at autopsy. The pathophysiology of Huntington's disease remains unknown, although protein aggregation, excitotoxicity, deficits in energy metabolism, transcriptional dysregulation and apoptosis may all be involved. Current pharmacologic therapy for Huntington's disease is limited and exclusively symptomatic. However, the disease is being heavily researched, and a wide range of disease-modifying therapies is currently under development. The efficacy of these therapies is being evaluated in transgenic models of Huntington's disease and in preliminary clinical trials.