Frontal-subcortical networks are known to be affected in HD and contribute to the cognitive dysfunction characteristic of the disease. Quantitative EEG (QEEG) can be used to assess the integrity of this circuitry; characteristic QEEG abnormalities long have been known to be present in the early stages of the illness (Bylsma et al., 1994). More recent research has suggested that a comprehensive topographic approach to QEEG analysis may reveal additional changes in brain activity (Bellotti et al., 2004) that may be indicative of subclinical disease (de Tommaso et al., 2003). This proposal aims to determine whether quantitative EEG techniques can be used to identify HD-specific abnormalities and thus serve as surrogate markers of disease.