ABSTRACTVibrio parahaemolyticus, as a vibriosis, causes huge losses to the aquaculture industry, food poisoning in humans and activates macrophages to induce pro-inflammatory cytokines. Chloroquine (CQ), as an anti-inflammatory property, this study aimed to investigate the effect of CQ on inflammatory response to V. parahaemolyticus in RAW 264.7 macrophages. The result showed that V. parahaemolyticus induced the production of T-cell co-stimulatory molecules (CD80, CD86, CD40 and MHC II), and increased the production and mRNA expression of pro-inflammatory, anti-inflammatory cytokines and type I interferons (IFNs). Meanwhile, the stimulated macrophages elevated cellular stress-released reactive oxygen species and nitric oxide synthase to trigger an antimicrobial response, and effectively reduced the accumulation of acetylated low-density lipoprotein and neutral lipids. Finally, we found that chloroquine (CQ) was involved in inhibiting inflammatory cytokine expression in response to V. parahaemolyticus. These results suggested that CQ potentially attenuated the inflammatory cytokine expression in Gram-negative bacterium-activated macrophages.