Agent technology has provided many opportunities to improve the human standard of life in recent decades, starting from social life and moving on to business intelligence and tackling complicated communication, integration, and analysis challenges. These agents play an important role in human health from diagnosis to treatment. Every day, sophisticated agents and expert systems are being developed for human beings. These agents have made it easier to deal with common diseases and provide high accuracy with less processing time. However, they also have some challenges in their domain, especially when dealing with complex issues. To handle these challenges, the domain has become characterized by distinctive and creative methodologies and architectures. This survey provides a review of medical multi-agent systems, including the typical intelligent agents, their main characteristics and applications, multi-agent systems, and challenges. A classification of multi-agent system applications and challenges is presented, along with references for additional studies. For researchers and practitioners in the field, we intend this paper to be an informative and complete resource on the medical multi-agent system.