This contribution focuses on the definition of music therapy as a specific applicative context to be seen as distinct from the generic use of music in a variety of pathologies. Music therapy is presented as a discipline grounded both upon relationship and upon the theoretical-methodological principles peculiar to each applicative model. The therapeutic nature proper to music therapy is highlighted with specific reference to the domain of the dementias. Music therapy facilitates expression, communication and relationship in the non-verbal context. Such an opportunity allows persons with dementia to establish contact, to express, and even contrive an organisation/regulation of their emotions, through the sonorous-musical relationship with the music therapist. On the basis of a brief analysis of the relevant literature, attention is drawn to the importance of both evidence-based clinical practice and music therapy evaluations, aimed at proving the effectiveness of music therapy, while promoting its correct application.