The high trophic status of brackish water and sediments at the Deltaic coast, especially the high nitrogen, phosphorus contents, along with relatively low pH and water temperature resulted in overgrowth of Ulva pertusa at El Garabaa and Ulva lactuca at Damietta river Nile Estuary. This represents an environmental problem of aquatic environment and water quality. On the other hand, this massive growth of Ulva species can be used as economic source of different natural products. The biochemical analysis of Ulva species indicated that Ulva pertusa have higher contents of proteins, lipids, minerals, soluble and insoluble carbohydrates than those of Ulva lactuca. The qualitative studies of natural products indicated that Ulva pertusa contains alkaloids, saponins, flavonoids, phenols and quinones while Ulva lactuca contains alkaloids, steroids, flavonoids, cumarins and quinones. Further study to determine the quantitative contents of natural products and its bioactivity is needed.