Protein, carbohydrate, lipid, ash, chlorophyll (a; b , c and total chlorophyll), organic carbon and moisture contents of the macroalgae Ulva sp.(Chlorophyta) were studied in corresponding to the water nutrient concentrations in the different sites and seasonal variations over one year, 2012. The water and macroalgae samples were collected monthly from rocky and sandy sites, Ras Al-Tin (site A) and El-Muntazah (Site B) along 18.6 Km distance of Alexandria shore, Egypt. The results showed that the studied areas are rich in nutritive elements at high concentrations. As the chemical analysis elucidated that Ulva sp. powder was characterized by a high contents of protein (20.7-27.6% DW), lipid (8.7-15.75% DW), carbohydrates (42.31-51.37% DW) and moderate ash content (15.32-20.53% DW), with the peaks of lipid and minerals contents in winter, the peaks of carbohydrates contents in spring, peaks of organic carbon in summer and the peaks of protein and phosphorus contents in autumn. The high nutrients contents of Ulva sp. confirm the high nutrient storage capacity of Ulva in this area, indicating that, on one hand, it could be used as biofilters in the aquaculture systems and for bioremediation purpose. On the other hand, the proximate composition nominates Ulva to be exploited as a good food and energy resource for human; animals and in aquaculture. Also, it could be used in several industries such as food and cosmetics industries, for its high carbohydrate contents. Remarkable seasonal variations were recorded in the contents of the studied parameters in the Ulva samples. The N:P and C:P ratios indicated that these algae at the studied areas may experience phosphorus limitation in particular seasons during the annual cycle. Significant positive correlations were noticed between, carbon-nitrogen and carbon-phosphorus as well as between total chlorophyll and both of total phosphorus (P<0.05) and total chlorophyll (P<0.01).