FAF1 is known as a component of the death-inducing signaling complex in Fas-mediated apoptosis and regulates NF- κ Bactivity as well as ubiquitination and proteosomal degradation. However, biological roles of FAF1 are still poorly understand in antibacterial immunity. Here we checked whether FAF1 modulate antibacterial immunity. Overexpression of FAF1 in Raw264.7 enhances the production of inflammatory cytokines and ROS upon Listeria monocytogenes infection or TLR ligand treatment. Controversially, knockdown of FAF1 in raw 264.7, BMDM derived from FAF1gt/gt mice shows lower level of pro-inflammatory cytokines and ROS. Consistent with in vitro data, FAF1gt/gt mice exhibited susceptibility upon infection of Listeria monocytogenes . Bacterial titer of spleen from FAF1gt/gt mice is higher than that of spleen from WT mice. Reversely, cytokines level of serum from FAF1gt/gt mice is lower than those of serum from WT mice. As a molecular mechanism, FAF1 binds to p67phox, which is component of NADPH oxidase complex and enhanced p67phox stability. These findings suggest that FAF1 positively regulates NADPH oxidase activation and NF- κ B signaling pathway by interaction with p67phox upon bacterial infection or TLR stimulation. [The National Research Foundation of Korea (Grant no. 2015020957)]