The master's thesis comprehensively addresses the copyright status of improvised music and highlights the key differences in relation to non-improvised and more conventional music practices. A brief theoretical and historical introduction is followed by an outline of its status in the droit d'auteur and the copyright legal system, and a more detailed description of the specific circumstances related to the creation of the work itself: the individuality and the consequences arising either from the requirement that the work be expressed or the requirement for the work to be fixed in a tangible medium of expression. The latter, specific to copyright systems, had been especially discriminatory against improvisers until recently, which is why a particular emphasis is dedicated to US copyright law. Likewise, the reference to high-profile US cases was largely inevitable due to the lack of the relevant domestic case law. The classification of music based on different levels of improvisation is followed by a review of the protection of improvised music according to the current legislation in Slovenia: firstly, the copyright protection for live performances, then phonograms, including the issue of their improvised manipulation, and finally, the copyright law related to the very topical streaming. Being the key problem in practice, the collective management of copyright is individually discussed and illustrated as clearly as possible through concrete examples for each of the above aspects.