The translationally controlled tumor protein (TCTP), which was initially described as a growth-related protein, primarily expresses proteins for numerous biological processes in eukaryotes. In the present study, the TCTP gene in the Chinese mitten crab Eriocheir sinensis (Es-TCTP) was identified from tissues of the hepatopancreas, by the construction of a cDNA library and the rapid amplification of cDNA ends. The results showed that the full length of Es-TCTP cDNA comprises 727 nucleotides, with an open reading frame of 507 bp that encodes 168 amino acid residues. The deduced amino acid sequence of Es-TCTP has a 51%-92% similarity to TCTPs of other eukaryotic species. The mRNA transcripts of Es-TCTP were detected by using RT-PCR for all tissues, with the highest level occurring in the hepatopancreas. In addition, temporal expression of the Es-TCTP was measured to analyze the role of Es-TCTP in an acute stress condition after CuSO(4) treatment. The expression of the Es-TCTP transcripts in hepatopancreas had no significant difference at the first 4 h, but increased significantly after 8 h, peaked at 24 h (4.3-fold higher than the control), and was still high after 72 h. Our results indicate that Es-TCTP is an acute-phase protein that is involved in Cu(2+) stress, with a possible anti-stress function in invertebrates.