n general, changes in biochemical components are closely linked to the state of sexual maturity of the mollusks and to energy supply, either directly from ingested food or from previously stored reserves. Carbohydrates are considered to be the main energy source in adult marine bivalves and are important for gamete formation and maintenance of adult condition during periods of nutritive stress or in winter. Many studies have related changes in the biochemical composition of bivalves with the reproductive cycle mostly in the natural environment. Energy storage and biochemical cycle are closely related to reproductive activity in marine bivalves. The present study indicates that major biochemical constituents in oyster Crassostrea madrasensis and Saccostrea cucullate are significantly influenced by environment condition such as quantity of food availability, temperature and salinity. The high contents of lipids, proteins, carbohydrates, and water content values, during summer are indicating this season as the best for harvesting this particular oyster species and the statistical analysis of the biochemical composition of the tissue sample of the oyster revealed positive correlation in both species of oyster Crassostrea madrasensis and Saccostrea cucullata. The strong Positive Correlation were observed in between the two stations and the highest value of protein, carbohydrate and lipids were observed in Crassostrea madrasensis rock and creek when it compare to Saccostrea cucullata. Keywords: Protein, Carbohydrate, Lipid , Crassostrea madrasensis, Saccostrea cucullata, oysters