This article presents the model of improvisational music therapy and its use with people with autism. Firstly, the author provides a brief definition of some theoretical ideas and the clinical characteristics of improvisational music therapy, a relatively new treatment which is becoming more wide-spread on a global level. Particular reference is made to the possibilities which music offers in the creation of relational experiences, and the role of time, rhythm and repetition as regulatory elements both in music and in intersubjective relationships. Following this, the efficacy of improvisational music therapy with people with autism is discussed, with regard to research in the field of neuroscience (specifically, the Mirror Neuron System) and the impact of a multimodal stimulus such as music making. The final section outlines the results of the international research project RCT TIME-A, in which improvisational music therapy was used with children with autism. The literature analysis shows that music therapy has significant effects and contributes to improvements in several aspects of the autistic disorder, such as autistic mannerisms, social awareness and social affect. We can consider these results as the beginning of a pathway towards validating improvisation music therapy as a treatment for children with autism.