In order to ascertain how widely the Kernohan and WHO numerical grading systems for brain tumours are used in Britain and how uniformly they are applied, a questionnaire was circulated to named neuropathologists in 19 Regional Neuropathology Centres in Britain. Eighty four per cent replied within 10 days. Their replies showed considerable variation in the use of grading systems and revealed that numerical grading was required mainly by clinicians and was not necessarily favoured by pathologists. Although some advantages of a grading system were advanced, it does seem that numerical grading of brain tumours is ill-defined and controversial. Furthermore, the use of historical grading systems may inhibit the incorporation of advances in pathological investigation into the clinical management of patients with brain tumours.