Ferritin, a major iron storage protein of most living organisms plays a crucial role in iron metabolism. A cDNAencoding a heavy-chain homologue of ferritin was isolated and sequenced in the freshwater giant prawn,Macrobrachium rosenbergii. The cloned cDNA was 1012 bp long containing an iron-responsive element(IRE) sequence in the 5′-untranslated region and a complete open-reading frame encoding for a 172 aminoacid residues protein with a conserved domain for the ferroxidase center characteristic for heavy chains ofvertebrate ferritin. Prawn ferritin transcripts are expressed in muscle, heart, hepatopancreas, stomach,hemocytes, ovary and testis. Quantitative real-time PCR revealed that the abundance of ferritin transcriptwas highest in the hepatopancreas, followed by the testis. The expression of the ferritin transcript in themuscle significantly increased 6-fold at 3 h after injection of iron. In the ovary, a high expression of ferritintranscript was first detected with nearly a 4-fold increase after 3 h post-injection that remained elevated for48 h. Heart ferritin mRNA expression increased up to 8-fold at 24 h. No significant difference was found in thehepatopancreas, hemocytes and testis. These results strongly suggested that the expression of prawn ferritinis regulated by iron at the transcriptional level as found in insects, and iron increased prawn ferritintranscripts in a tissue-specific manner.