The book provides an overview of theoretical concepts and methods of music therapy and a wealth of medical research results, especially neurobiological and psychological-musical research on the use of music in therapy. It cites the author's research on musical communication using a musical instrument and publishes for the first time her own Musical Communication Style Questionnaire. It presents her own methods of musical portraiture and musical coding, exemplified by fragments of her therapeutic process. It ends with a presentation of a study using the Personality Inventory (BFI) and the author’s own Musical Identity Test, standardized by psychologist Maria Dymnikowa. It presents detailed statistical analyses of the results obtained from several hundred patients, illustrated with tables and graphs, made by co-author Maria Dymnikowa. This is an empirical confirmation of the importance of music therapy for understanding the personality characteristics of the people studied, and thus its importance for achieving the insight necessary to achieve positive effects of therapy.