Abstract: Pellino protein is a member of highly conserved E3 ubiquitin ligase which plays an important role in ubiquitination and innate immunity. In this study, we cloned and identified a crustacean Pellino from Penaeus monodon (PmPellino). The full-length cDNA of PmPellino consisted of 1 961 bp with an 89 bp 5'UTR, a 573 bp 3'UTR and a 1 299 bp open reading frame encoding 432 amino acids. PmPellino mRNA was detected in all the tissues examined by real time PCR (highest in gill). The expression of PmPellino in hepatopancreas was significantly up-regulated after acute ammonia nitrogen stress (P<0.01), but was inhibited in gill (P<0.01). Vibrio harveyi could significantly activate the expression of PmPellino in gill and inhibit its expression in hepatopancreas. V. anguillarum could significantly inhibit the expression of PmPellino in hepatopancreas, but there was no sigficant difference in gill with the control group. Staphylococcus aureus could significantly activate the expression of PmPellino in both hepatopancreas and gill. The results indicate that PmPellino might play an important role in the immunity of P. monodon.