Industrial symbiosis describes a regional inter-firm approach towards a more sustainable industry. However, the implementation of industrial symbiosis is hampered by a multitude of various barriers. Although prior work has dealt with identifying barriers, an encompassing overview is missing to date. Therefore, in this paper, barriers were identified by the means of a literature review and analyzed through qualitative content analysis. In total, 402 barriers for the implementation of industrial symbiosis were identified. They were grouped into nine categories: economic, technology, financial (hard, quantifiable factors); cooperation, management, knowledge, information (soft factors, which are difficult to quantify); policy/regulation, and public/market (contextual factors). The insights gained can be used to develop strategies and tools for further development and advancement of current industrial symbiosis practice to overcome existing barriers.