C-Jun gene was identified and characterised in Penaeus monodon. qRT-PCR indicated that PmC-Jun mRNAs were widely expressed and the peak level was observed in the gills and hepatopancreas. PmC-Jun was up-regulation after Vibro harveyi and Streptococus agalactiae infection. PmC-Jun plays an important role in Penaeus monodon immune response.