Curcuma longa is a perennial foodstuff plant that is utilized widely in Asia. Here, we evaluated the effects of extracts of the aerial parts of C. longa on inflammatory processes in RAW264.7 macrophage cells. Dried aerial parts of C. longa were extracted with methanol and partitioned successively with CH2Cl2 and n-BuOH. This n-BuOH fraction (0–40 µg/ml) significantly suppressed the lipopolysaccharide-mediated induction of nitric oxide, prostaglandin E2, and pro-inflammatory cytokines. Western blotting found that the levels of nitric oxide synthase and cyclooxygenase-2 were also reduced in a concentration-dependent manner, in the absence of cytotoxicity. The major components present in this extract were isolated and chemically characterized using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry and nuclear magnetic resonance spectroscopy. Four flavonoids were identified: Quercetin 3-(2Gal-rhamnosyl-robinobioside) (1); Quercetin 3-rutinoside (2); Quercetin 3-rhamnosyl-(1→2)-rhamnoside (3); and Quercetin-3-O-rhamnoside (4).