The circular economy is increasingly recognised as essential for a sustainable future, demanding a shift from the take-make-dispose mindset to a circular approach. Recently, the concept of circular manufacturing systems has emerged. This paper reviews state-of-the-art literature on circular manufacturing systems, providing an overview of current research by examining the structuring levels of factories and the associated research issues. This will contribute to identifying important aspects of the circular manufacturing system, as well as future research directions that can support the realisation of more circular practices in manufacturing. The analysis of literature reveals that most research focuses on higher structuring levels, such as the network, factory and system levels. Additionally, significant attention is given to the importance of product design for multiple life cycles and effective communication in the supply chain. Conclusively, currently unexplored areas and interesting issues that could be addressed in future research are identified, including the need to incorporate the production aspect into the concept of circular manufacturing systems.