Abstract A case of advanced Wilson's disease with clear dementing features is presented. Neuropsychological evaluation before treatment revealed intellectual deterioration particularly in memory and performance tasks. The patient was treated with Penicillamine, a copper-chelating agent, for 7 months, with notable improvement in her dementia and in her motor signs. A second battery of neuropsychological tests demonstrated the improvement in the mental aspects. These findings support the concept of Wilson's disease being a reversible dementia.