DNA topoisomerase IIα (Topo IIα) is linked to tumour cell growth and chemoresistance. We examined immunohistochemically Topo IIα expression levels in a series of 36 consecutive paediatric optic pathway glioma (OPG) patients. Topo IIα labelling index (LI) ranged from 0.0 to 11.6 and was significantly associated with patient age, with higher levels of Topo IIα in children ≤ 3 years (P = 0.031). Topo IIα expression did not correlate with patient survival. Topo IIα LI was not significantly increased in specimens of repeat surgery. Topo IIα LI closely correlated with MIB-1 LI (R = 0.781, P < 0.001). We conclude that Topo IIα expression correlates with tumour cell proliferation in paediatric OPGs. Assessment of cell proliferation, however, does not assist in refining prognostic predictions. Enhanced Topo IIα expression in children ≤ 3.0 years suggests that Topo IIα-interfering anticancer compounds for adjuvant treatment of OPGs may be of particular benefit to young children. © 2002 Elsevier Science Ltd. All rights reserved.