The relationship between proliferating cell nuclear antigen (PCNA) expression and various clinicopathological indices (age, sex, tumour location, histological type and grade and treatment) and post-operative survival were studied in patients with central nervous system gliomas using univariate and multivariate analysis. The expression of PCNA (PC10 score) was examined immunohistochemically using the monoclonal antibody PC10 on paraffin sections from 45 cases. Univariate analysis showed that a high PC10 score as well as older age, high histological grade and the histological type (astrocytoma) were associated with reduced survival. However, multivariate analysis revealed that only PC10 score and histological type had independent prognostic significance. The most important feature influencing PC10 score was the tumour grade. Regarding the patients who relapsed, the survival from the time of original diagnosis was related to the relapse-free period, while the PC10 score of the primary tumour emerged as the only independent predictor of survival following the first recurrence. These results indicate that PCNA expression is an independent prognostic indicator in CNS gliomas.