Abstract: We isolated and characterized the profilin full-length cDNA from hemocytes of swimming crab Portunus trituberculatus. The profilin cDNA consists of 742 bp and encodes a polypeptide of 125 amino acids, having a predicted isoelectric point of 5.87. The deduced amino acid sequence shows 42.9% amino acid sequence identity to the profilin of mosquito Anopheles gambiae. The profilin mRNA was highly expressed in hemocytes and moderately in hepatopancreas of normal crab. The higher expression of profilin mRNA is observed in crab challenged by the pathogenic bacterium Vibrio parahaemolyticus. These results suggest a potential role for profilin in pathogen host defense mechanisms.