The doctoral dissertation entitled Stelarc and the Posthuman Body we will attempt to demonstrate the shift and the sliding of boundaries between the natural and artificial, prompted by the activity of machines in the digital age. For over two decades, Australian cybernetic and performance artist Stelarc has employed his manifestos, projects, performances and experiments to demonstrate that contemporary art is exceedingly intermeshed with the latest theoretical efforts in elucidating the relationship between the human body and both information-communication technologies and biogenetics. Consequently, in so doing, he has established himself as a unique and authentic artist, exploring the boundaries between the biological and the posthuman state, therefore, it is necessary to ascertain the relationship betweentheoretical reflexion and artistic expression itself in the interstitial space between body and technology. Furthermore, the aim of this dissertation is to open up space for redefining the relationship between the mind and body, between self-development and body design, as well as many other distinctions between the traditional conceptions of the organic/organism and machines. Late 20th century was the period of pivotal discoveries in the sphere of contemporary technosicences, especially in the field of biogenetics and biotechnology, with far-reaching implications for the notion of the body. This is most easily discernible in the theoretical and practical endeavours of the representatives of transhumanism and posthumanism – the interdisciplinary tendencies in philosophy, sciences, arts and technology. Improving and perfecting the cognitive and physical abilities of the human subject introduces numerous questions about the purpose of human existence under new technological circumstances. In terms of investigative and scientific method, by examining the case of contemporary artist Stelarc, the fundamental hypothesis of the dissertation will relate to the inauguration of an entirely new bodily identity, that is, an entirely novel sort of posthuman body that is genetically modified, designed and upgraded with the purpose of prolonging human life. Shaping and creating posthuman bodies, by means of combining robotics and artificial intelligence with the human body, Stelarc using his own body as example, in an intellectually stimulating and self-reflexive way echoes an already widely present phenomenon involving an experimental form of existence of posthuman organisms. That means that the human body assumes completely new meanings since, in place of biological determination, it is under constant influence of the need for upgrading, altering, redesigning and aesthetic intervention. The dissertation will also delineate the research performed via a film essay on Stelarc, featuring Stelarc’s visit to Zagreb in 2017, a lecture he held on the occasion, the exhibition of photographs at the Technical Museum Nikola Tesla in Zagreb and the scientific panel under the title „How can theoretical research foster scientific development in Croatia?” held at Vern’ University of Applied Sciences in Zagreb. The film essay will attempt to highlight a system in which bodies with technical implants are seen as our new techno-social and cultural environment, while their purpose is to facilitate better functioning in a complex network of digital and analogue means of communication. The title of the film Stelarc and Human + alludes to the notion of perfect human bodies, heralded by the posthuman age. These are not the bodies of robots or the bodies of beings with supernatural powers, but rather bodies that have been modified and upgraded in order to achieve longer life expectancy. The performance of such a posthuman body, which mimics the original function of movement, speech and body of a human one by means of artificial intelligence, resembles art without a body.The film essay will also demonstrate how the architecture and the evolution of the human body as a perfect slice of nature change through the interpolation of science and technology. The primary aim of this doctoral dissertation is to attempt, by theoretical analysis of the notion of the posthuman body, to arrive at the possibility of performance via the paradigmatic case of contemporary artist Stelarc, therefore, the film essay about him is not included merely to illustrate the pronounced connection between idea and performance. According to the central premise, it is only with the advent of the posthuman body that it becomes possible to view the human identity as fluid and de-centred, while these same categories appear in contemporary art in reference to the exploration of the crossing of boundaries between nation-states, sex/gender and society-culture. The reactions of the posthuman body comprise a symbiosis between the human and non-human, generating a new physical identity as a complex cybernetic network system. It is necessary to trace the process by which the body – in a constant search for ways to change and perfect it, which surpass the limits of the human mind – loses its identity, becoming, as Lacan termed it, a fractal body, and finally undergoing a complete transformation. Subject to constant metamorphoses driven by new technologies, the body is undergoing vertiginous changes. Simultaneously, in philosophy, sciences and arts, we are witnessing a transition from the classical, mechanical paradigm to an informational and cybernetic one, the principal characteristic of which is the increasing technologization of life, while technology itself becomes a precondition for generating a new definition of life. Conjoining technosciences with the human body engenders entirely new entities that, as an amalgam of artificial intelligence and the human body, herald a completely new generation of posthuman organisms controlled by a control panel or the power of the mind. Such a posthuman body in symbiosis with both the human and the non-human yields an entirely new bodily identity within the cybernetic network.