The 11 kDa protein, a small nonstructural protein of parvovirus B19, may play important roles in viral replication cycle. To investigate the effect of 11 kDa protein on the NF-kappaB signaling pathway, we first prepared the poly-antiserum using GST-11 kDa fusion protein purified via prokaryotic expression system, and demonstrated that the 11 kDa protein mainly localized in cytoplasm when expressed in Hela cells. Meanwhile, luciferase activity assay and Western blotting assay showed that 11 kDa up-regulated the transcriptional activity of NF-kappaB and induced the degradation of IkappaB-alpha in Hela cells. Moreover, the 11 kDa protein activated the IL6 promoter, which is probably through the NF-kappaB pathway. Taken together, these results suggested that 11 kDa protein may contribute to activating inflammatory factors through participating in the cell signaling pathway.