THE CURRENT study was conducted to assess the influence of different harvesting site (habitat) on the chemical constituents of Codium tomentosum Stack collected from two different sites on the coast of Egypt (Mediterranean [M] and Red [R] Seas). The current results showed that, salinity and temperature of the Red Sea is relatively higher than those of the Mediterranean one. Additionally, results indicated significant differences in the biochemical profiles of Codium between the two sampling sites. The total carbohydrate, proline, glycerol content together with total antioxidant capacity, reducing power as well as mineral content (Na+, K+ and Ca++) and the activities of antioxidant enzymes (PPO, POX, ASO, APX and CAT) of Codium collected from site R were significantly higher than of those collected from site M. In contrast, total protein, total amino acids, flavonoids contents were predominated in Codium harvested from the Mediterranean Sea. No significant differences in ascorbic acid, glutathione, chlorophyll a content and total phenols collected from the two sites. The electrophoretic analysis of protein pattern revealed the appearance of of 7 and 8 polypeptide bands in Codium from the two sites (M and R, respectively). However polypeptides with molecular weights 93, 72 and 42kDa were recorded only for Codium of site (M), while that of 17 kDa was specific for Codium of site (R). In conclusion, this study shows that the different sampling sites influences on biochemical profiles of Codium. However, Codium in response to extreme temperatures and salinity, may alter its metabolism, building a strong protection system and producing compatible solutes in various ways to overcome these stress. This result is a step towards to study the algal diverse biochemical integrations involved in cellular adaptation of algae to different environmental factors and habitats.