The aim of the study was to assess the relationship between the rate of clinical tumour growth and various histological features, including Ki67 labelling index, in skull base chordoma. Cases of skull base chordoma from 19 patients (six female, 13 male; age range 8-63 years) were reviewed and the diagnosis confirmed based on histological and immunohistochemical features. In each biopsy cellularity, pleomorphism, mitotic activity, apoptotic bodies, necrosis and inflammatory cell infiltrate were graded and Ki67 labelling index (LI) calculated as a measure of proliferation. Tumour doubling time was assessed by quantitative analysis of tumour volumes in post-operative magnetic resonance images and correlated with age, sex, histological parameters and Ki67 LI. It was shown that increasing patient age, the presence of mitotic figures or a Ki67 LI in excess of 6% were associated with faster growing tumours.