Macrophage migration inhibitory factor (MIF) is a key proinflammatory cytokine in immuno-inflammatory diseases.For the first time,we examined the expression of MIF in Epinephelus awoara (E.awoara).MIF expressions have been detected in head kidney,spleen,liver,brain,intestine,gill,heart,stomach,and muscle of E.awoara infected with V.parahaemolyticus.The mRNA levels observed in infected groupers were higher than those in healthy groupers.MIF,TNF-α,and IL-1 tissue levels have been measured by ELISA.A significant increase in MIF,TNF-α,and IL-1 tissue levels have been found in the treatment groups compared with those in controls.MIF,TNF-α and IL-1 tissue levels in spleen,head kidney,intestine,and liver of E.awoara during the challenge trial with V.parahaemolyticus were significantly higher than those in controls respectively.There was evidence that functions of MIF in a positive feedback loop with TNF-α,and IL-1 that could perpetuate the inflammatory process in grouper infected with V.parahaemolyticus.In conclusion,these results indicated that MIF was related to pathogen-induced immune response.