The changes in the chemical composition of fat body reflect tissue specific changes in different developmental stages of the silkworm pupae. The data on the difference in the protein content of the fat body among the parents and single hybrid and foundation crosses revealed variations in protein content. In case of the total protein estimation, when males and females are being compared the females always exhibited higher protein content than males. The data of the difference in the carbohydrate content in the fat body among the males of single hybrid, foundation cross and that of the parents revealed that the concentration of glycogen in the fat body was higher in case of parents than that of hybrids and observed to be more in the females. Statistical analysis has shown significant results among the parents, FC and the hybrids for carbohydrate content in fat bodies. Accordingly, no major differences were noticed in the total lipid content between the breeds was observed even though small quantity of increase in lipid content was exhibited by the females. Since silkworm pupae mainly consisted of tricyclglycenol, phosphatidylethanolamine, and phosphati-dylcholine. Both of them contains approximately 40% of a-linolenic acid as the predominant fatty acid, silkworm pupae would be a good source of functional fatty acids in the diet.