The silkworm, Bombyx mori L. has an economic importance in sericulture. Our results indicate that the average fresh cocoon, pupal and cocoon shell weights in females are significantly heavier than those in males. Also, the average haemolymph protein concentration of the last larval instar was significantly higher in females than that in males. The percentage elevation in females was 31.7% than males. Analysis of electropherogram from the haemolymph indicated the presence of 13 negatively charged proteins in females and 11 bands in males. Only one band with a molecular weight of 75.536 KDa was common and shared by both females and males. This band represent 35% of the total haemolymph bands in males and 13.8% only in females.The other 22 bands are completely different in males and females.