Music therapists’ work is constantly researched and measured in order to find the best possible ways for conducting music therapy and treating people through music. In spite of this, music therapists themselves are rarely investigated. This research had as its aim to investigate music therapists. The actual investigation involved the sense of self of a music therapist in musical improvisation through semi-structured interviews analysed with Interpretative Phenomenological Analysis. Findings of the research included accepting awareness, using the self as a tool and mutual and authentic interaction between equals. These findings coincide with previous researches supporting that music can be another form of interaction, and that using the self as a tool and accepting awareness are important for the therapeutic process. Music therapists could use this information in relation to their own self-reflection in order to further their therapeutic practice and investigate what really is important for their sense of self in the imrpovisation and in therapy in general. Investigating the sense of self of the music therapist in the more general level of music therapy could be a topic for future investigation.