B cell activating factor belonging to the TNF family (BAFF) plays a critical role in the pathogenesis of autoimmune diseases. The inhibition of BAFF expression is an emerging therapeutic approach for these disorders. Chicoric acid (CA), a bioactive phytochemical found in several widely used traditional medicinal plants, has significant anti-inflammatory activity and anti-arthritic effects. However, the role of CA in modulation of BAFF expression remains unknown. In this study, we demonstrated that CA reduced BAFF expression in human B lymphocyte cell lines and decreased the DNA-binding activity of nuclear factor-κB (NF-κB) in the BAFF promoter region. Furthermore, CA inhibited both the nuclear translocation of p65 (the subunit of NF-κB) and the phosphorylation of IκBα (inhibitor of NF-κB). These results suggest that CA suppresses BAFF expression by inhibiting NF-κB activity, and CA may serve as a novel therapeutic agent to down-regulate excessive BAFF expression in autoimmune diseases.