In my specialist thesis I have devoted myself to a research study which examines the possibility of influencing on the reduction of behavioural problems of persons with moderate learning disabilities by using the art of music, and the possibility that implemented process with guided musical activities has an impact on improving their social cohesion. I presented following contents: assistance with art, internationally recognized concepts of musical therapy, musical activities with creativity in the light of assistance with art, communication in connection with the EBL method and theoretical insights about the formation and perseverance of behavioural problems that arise in children, adolescents and adults with learning disabilities. I have shown a musical therapeutic process and its effects; the prevalence of musical therapy in practice; defined the objectives of these activities in reducing inappropriate behavioural responses; and described the characteristics of behavioural problems. Creativity as such is explained at the end of the theoretical part and is connected with the empirical part which deals with practical approaches to musical creativity. Using theoretical premises and on the basis of set goals, I have formulated and carried out the collective process of musical activities in which there were included three persons with moderate learning disability and with behavioural problems. I have chosen the techniques and approaches of work with regard to the analysis of individual musical meetings and in the accordance with theoretical premises. On the basis of collected data of multiple case study, including the consideration of group dynamics and interpretation of the results of the evaluation of selected questionnaires, I have explained the findings regarding given research questions. Assistance through guided musical activities effectively encourages nonverbal and verbal communication and creativity in a group of people with learning disabilities and expressed behavioural problems. The study has also confirmed the reduction of behavioural problems, especially in the case of a boy, whom I named Močni. It was also established that behavioural problems of all three persons included in the group musical activity did not expressed themselves.