The application of modern investigative techniques in molecular biology, cytogenetics and immunocytochemistry has yielded much new information on central nervous system tumours both in vitro and in vivo. Although the clinical potential of these findings is yet to be fully realized, preliminary clinical studies based on this new information are now in progress. The mechanisms and consequences of brain damage in head injury have been studied both clinically and experimentally for many years; new investigative techniques focusing on the cellular and subcellular basis of brain damage have provided information which is interesting not only in terms of basic neurobiology but also in the identification of new areas for possible therapeutic intervention.