•Overview of multi-agent approach for smart-microgrid energy management and operation.•Different state-of-the-art microgrid sub-problems tackled by MAS are revised and presented.•Trends for future decentralized energy storage and service restoration in microgrids are highlighted.•Future MAS applications requested by efficient microgrid integration into the grid. Mini/microgrids are a potential solution being studied for future systems relying on distributed generation. Given the distributed topology of the emerging smart grid systems, different solutions have been proposed for integrating the new components ensuring communication between existing ones. The multi-agent systems paradigm has been advocated as a useful and promising tool for a wide range of applications. In this paper, the major issues and challenges in multi-agent system and smart microgrids are discussed. We present a review of state-of-the-art applications and trends. By discussing the possibilities considering what has been done, future applications, with attention to renewable energy resources integration in emerging scenarios, are placed on the agenda. It is suggested that further studies keep growing in this direction, which will be able to decentralize the high complex energy system, allowing users to participate in the system more actively. This step may decentralize the infrastructure, giving more weight to society wishes, as well as facilitating maintenance, reducing costs and opening a the door for innovative ideas for low-cost based equipment. On the other hand, letting several combinatorial optimization problems opened to be improved and discussed along the next coming years.