Assessment of tumour cell proliferation in glioblastoma (GB) has been a topic of considerable research interest over the past decade. However, the correlation of tumour proliferation and patient outcome has yielded controversial results. In this study, we examined immunohistochemically, using paraffin-embedded tissue, the expression of the proliferation-related markers DNA topoisomerase IIα (TIIα) and Ki-67 antigen in a cohort of 114 GB patients treated consecutively with surgery and radiochemotherapy, and correlated the expression with patient outcome. The TIIα labelling index (LI) ranged between 5.2 and 87.2% (median: 25.6%). Survival analysis disclosed an association between high TIIα expression levels and prolonged survival (P=0.040, log-rank test). TIIα expression correlates closely with Ki-67 labelling index (R=0.927, P<0.001), which itself is predictive of patient survival (P=0.044). However, in multivariate analysis, only the Karnofsky performance status remained predictive of patient survival. We conclude that high expression of TIIα and Ki-67 appears to be associated with a prolonged survival in our cohort of GB patients. © 2002 Elsevier Science Ltd. All rights reserved.