Previously, we showed that dexamethasone (DEX) inhibited the expression of inflammatory cytokines, matrix metalloproteinase-1, and cyclooxygenase-2 messenger ribonucleic acid in SW982 cells. In this study, the effect of DEX on the transcription factors nuclear factor–κB (NF-κB) and activator protein–1 (AP-1) was examined in SW982 cells by electrophoretic mobility shift assay (EMSA). Both NF-κB and AP-1 deoxyribonucleic acid binding activities were detectable in SW982 cells by EMSA, and they were induced by interleukin-1β treatment. DEX inhibited NF-κB binding activity at 10 μM as well as at 100 μM, although the inhibition was only partial. However, DEX had little effect on AP-1 activity. These results suggest that DEX reduces the expression of inflammatory cytokines and other proteins in SW982 cells by inhibiting NF-κB.