We describe here the cloning of a cDNA encoding putative calreticulin (CRT) from the silkworm, Bombyx mori. The CRT cDNA comprised of 1,194 bp encoding 398 amino acid residues. B. mori. CRT has a HDEL sequence at the end of the C-domain. The B. morl, CRT showed 88% protein sequence identity to the G. mellonella CRT, 71 % to A. aegypti CRT, and 63% to H. sapiens CRT, Phylogenetic analysis revealed that the deduced amino acid sequences of the B. mori CRT formed a highly inclusive subgroup with other insect CRTs. Northern blot analysis exhibited an expression of the B. mori CRT gene in the fat body, evidencing the fat body as a major site for CRT synthesis.