 Photocatalytic membrane reactors, PMRs, have emerged as a promising technology for treating water and wastewater. These systems combine the advantages of membrane filtration and photocatalysis to reduce organic and inorganic contaminants from water sources. The photocatalytic reaction occurs on the surface of the membrane, which allows for efficient removal of contaminants without the need for additional chemicals or energy inputs. Additionally, these systems are easy to maintain and operate, making them a cost-effective option for water purification. This review provides an overview of the working and fouling mechanisms of PMRs, as well as the development of fouling prevention strategies. It also examines the role of photocatalysis in membrane fouling processes such as pore plugging and cake layering. This article was authored by Moshtaba by Nasada, Jamal Rizuli, Samad Sabagi and others.