There is an increasing incidence of dementia in our aging population, and consequently an urgent need to develop treatments and activities that may alleviate the symptoms of dementia. Accumulating evidence shows that persons with dementia enjoy music, and their ability to respond to music is potentially preserved even in the late or severe stages of dementia when verbal communication may have ceased. Media interest in this topic has contributed to the public perception that music abilities are an "island of preservation" in an otherwise cognitively impaired person with dementia. In this chapter, we review the current literature on music cognition in dementia and show that there has been very scarce rigorous scientific investigation of this issue, and that various types of music memory exist and are differentially impaired in the different types of dementia. Furthermore, we discuss the recent development of music activities as a nonpharmacological treatment for dementia and highlight the methodological limitations of the current literature on this topic. While it has been reported that music activities can improve behavior, (particularly agitation), mood, and cognition in persons with dementia, recent large-scale randomized control studies have questioned the specificity of the effect of music and found that it is no more beneficial than other pleasant activities. Nevertheless, music is unique in its powerful ability to elicit both memories and emotions. This can provide an important link to individual's past and a means of nonverbal communication with carers, which make it an ideal stimulus for persons with dementia.