Vietnamese edible marine macro-algae (seaweed) are of interest because of their value in nutrition and medicine. Vietnamese living in the coastal have traditionally utilized seaweeds species as food supplement and herbal medicine. They consumed seaweed as food in various forms: raw as salad and vegetable, pickle with sauce or with vinegar, relish or sweetened jellies and also cooked for vegetable soup. As herbal medicine, seaweed is usually used for traditional comestics, treatments for cough, asthma, hemorrhoid, boils, goitres, stomach ailments, urinary diseases, reduce the incidence of tumors, ulcers and headaches. Although Vietnam has an abundance of algae floral with total number of species is estimated to be nearly 1000 spp. in which there are 638 species of marine algae identified. However, there have been no intense study regarding to changes in marine algal chemistry. The fifteen species of edible seaweeds studied in this paper include green, brown and red algae. The proximate compositions as ash, protein, lipid, carbohydrate, fatty acids, vitamins, pigments, macro and micro-elements were compared among different species examined and the genetic relationships among them by analyzing the species-specific differences in nucleotide sequences of ITS-1 region of the ribosomal DNA was identified.