To understand the scope of semantic impairment in semantic dementia.Case study.Academic medical center.A man with semantic dementia, as demonstrated by clinical, neuropsychological, and imaging studies.Music performance and magnetic resonance imaging results.Despite profoundly impaired semantic memory for words and objects due to left temporal lobe atrophy, this semiprofessional musician was creative and expressive in demonstrating preserved musical knowledge.Long-term representations of words and objects in semantic memory may be dissociated from meaningful knowledge in other domains, such as music.