The biochemical constituents of muscle and hepatopancreas – carbohydrates, proteins and lipids of the mud crab in Scylla serrata of Coringa mangroves in relation to sex, size and season have been studied. Muscle carbohydrates were almost similar between male and female but in hepatopancreas it has shown minor variation in females and high carbohydrate content was observed in the 4^th quarter of the study period. The protein content of muscle in males and females were 31.98 % and 31.97 %, and in hepatopancreas it was 15.23 % and 12.75 %. Proteins of muscle and hepatopancreas showed an increasing trend with the increase in size of the crab and high protein content was noticed in all the size classes of male crabs, in the last quarter of the year (October, November & December) and low levels during the second quarter of the year (April, May & June). The average lipid content in muscle was similar in both males and females. A gradual increase in lipid content was observed with the increasing size of the crab and hepatopancreatic lipids are more than those of the muscle.