The marine environment provides a broad range of diverse habitats from which novel sources of natural products can be derived. Seaweed is a term applied to multi cellular, marine algae which are large enough to be seen by the eye unaided. Some can grow to up to 60 meters in length. Seaweeds are a food source for marine animals such as sea urchins and fishes, and are the base of some marine food webs. They also provide shelter and a home for numerous fishes, invertebrates, birds and mammals. Seaweeds or marine macro algae are potential renewable resource in the marine environment. It has been used as antioxidant, cardiovascular agent, antimutagen, anticoagulant, antimicrobial, antitumoragent. Majority of their antioxidant activity is due to flavones, isoflavones, flavonoids, anthocyanin, Coumarin, ligans, catechins and isocatechin. Seaweeds are rich in antioxidants such as carotenoids, pigments, polyphenols, enzymes and diverse functional polysaccharides.