Seaweeds are the most abundant source of polysaccharides, as alginates, laminaran and fucoidan , agar and agarose as well as carrageenans. Seaweed Polysaccharides with a very large variety of chemical structure are now recognized as valuable polymers for industrial applications and for their variety of physical and biological properties. This review summarises the potential of bioactive polysaccharides with special attention to pharmaceutical applications in species that could be of interest for utilisation for health and functional food applications. This applies either to the choice of high value added bioactive products to be exploited in an available species or to the choice of seaweed species when a bioactive compound is desired.