Citrus fruits (Citrus aurantium L.) have long been used as a traditional herbal medicine. The benefits of the flavonoids found in Citrus aurantium L. include anti-inflammation, anti-cancer, anti-viral and anti-bacterial activities, and enhancement of the immune response. The study investigated the effect of the flavonoids isolated from Citrus aurantium L. native to Korea on the production of pro-inflammatory mediators by blocking signal transduction mediated by nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) in lipopolysaccharide (LPS)-induced L6 skeletal muscle cells. The flavonoids decreased the production of inducible nitric oxide synthase, cyclooxygenase-2, interleukin-6 and tumor necrosis factor-alpha by suppressing NF-κB and MAPKs signal pathways in LPS-induced L6 skeletal muscle cells. These findings suggest that the flavonoids isolated from Korea Citrus aurantium L. might have anti-inflammatory effects that regulate the expression of inflammatory mediators in L6 skeletal muscle cells. Copyright © 2012 John Wiley & Sons, Ltd.