C/EBP beta (CCAAT/enhancer binding protein beta) is a transcriptional factor that belongs to the basic region-leucine zipper class DNA-binding proteins and plays a role in cell differentiation and inflammatory reactions. Although high tissue levels of inflammatory cytokines, such as interleukin (IL)-6, IL-8 and transforming growth factor-beta, have been observed in glioma patients, the mechanisms underlying this phenomenon remain to be elucidated. C/EBP beta induces a variety of cytokines and thus may play a role in the pathogenesis of glioma. In this study, we investigated the relationship between C/EBP beta expression, tumor histology, and prognosis in glioma. The expression of C/EBP beta mRNA was examined with quantitative real-time PCR and protein expression was examined with immunohistochemical techniques in 47 glioma tissue samples. Expression of C/EBP beta mRNA and protein was markedly increased in high grade glioma compared with low grade glioma. Patients whose expression of C/EBP beta mRNA and protein in tumor tissue was lower survived longer than those whose expressions were higher. In vitro, C/EBP beta siRNA inhibited glioma cell proliferation and invasion. Moreover, IL-8 production by glioma cells was inhibited by C/EBP beta siRNA transfection. These data suggest that increased expression of C/EBP beta may contribute to the promotion of tumor invasiveness and progression. The data imply that the comparison of C/EBP beta expression could be a prognostic marker for patients with glioma.