Abstract: Objective : To evaluate the relationship between the expression of nuclear factor κB( NF -κB) and proliferating cell antigen (PCNA) and pathology grade in brain astrocytomas. Methods :The immunostaining of NF-κBp65 and PCNA in 67 astrocytomas and 10 cases of normal brain tissues were performed by Streptavidin-Peroxidase (SP) method. Results : The result showed the difference of PCNA expression between tumor grades were statistically significant (P<0.05) except those in group Ⅲ、and group Ⅳ (P>0.05). Generally, the positive rate of PCNA increased with tumor grade. Though total variance of NF -κB expression among tumor grades was remarkable (P<0.01), there were no significant difference among group I ,II,Ⅲ and Ⅳ (P>0.05). However, the positive rate of NF -κB was much higher in tumors with higher grade of malignancy than in those with lower grade of malignancy (P<0.01).Conclusion : The abnormity of N F -κB may increase cellular proliferation activity by PCNA, immunohistochemical analysis of PCNA combined with NF -κB may be useful not only in deciding the grade of malignancy but also in some prognostic value in astrocytomas.