Summary Bacterial extracellular polysaccharides have been shown to mediate many of the cell‐to‐cell and cell‐to‐surface interactions that are required for the formation, cohesion and stabilization of bacterial biofilms. However, recent studies have identified several bacterial polysaccharides that inhibit biofilm formation by a wide spectrum of bacteria and fungi both in vitro and in vivo . This review discusses the composition, modes of action and potential biological roles of antibiofilm polysaccharides recently identified in bacteria and eukarya. Some of these molecules may have technological applications as antibiofilm agents in industry and medicine.