Abstract: The purpose is to study the potential role of Litopenaeus vannamei armadillo repeat-containing protein 8 (ARMC8) in the immune response triggered by the virus and bacterial pathogens. Full-length cDNA sequence of ARMC8 gene from L. vannamei (named LvARMC8, GenBank Accession Number:KX058562) was first cloned using RACE method. The full-length cDNA sequence of LvARMC8 was 2917 bp, which contains a 50 bp 5'UTR, 822 bp 3'UTR and 2046 bp open reading frame (ORF) that encoded 681 amino acid residues. SMART analysis results showed that LvARMC8 contains six armadillo repeat (ARM) domains. Multiple alignment analysis shows that LvARMC8 shared 71% amino acid identity with Zootermopsis nevadensis, which is the highest. Phylogenetic analysis showed that LvARMC8 was clustered together of invertebrates groups and most closely related to Tribolium castaneum ARMC8, Culex quinquefasciatus ARMC8 and Papilio xuthus ARMC8. RT-PCR analysis showed that LvARMC8 was constitutively expressed in all the examined tissues with the highest expression in epithelium and lowest expression in eyestalk. Upon WSSV challenge, the expression of LvARMC8 was significantly down-regulated at 12 hpi (hours past infection) but significantly up-regulated starting at 48 hpi, reaching the peak at 72 hpi. By V. parahaemolyticus challenging, the level of LvARMC8 expression were markedly increased at all the detected time points except 24 hpi. The result suggests that LvARMC8 might take part in the innate immune response of L. vannamei triggered by pathogens.