This volume contains the proceedings of the Second International Symposium on Biology of Brain Tumour. The first Symposium was held in 1979 at Gardonne Riviera, Italy. This meeting was planned in order to coincide with the lOOth Anniversary of the first reported operation for glioma in London on November 25, 1884. Since the first meeting, the field of neuro-oncology has made remarkable progress in understanding both basic and clinical factors of significance to patients with brain tumor. While the earlier meeting dealt to a large extent with clinically oriented studies, this symposium was more heavily weighted toward the biology of brain tumour and improving our understanding at the physiologic, biochemical, pharmacologic, and cellular level. The meeting was divided according to scientific content into presentations and discussions as well as posters for more leisurely viewing, so as to allow the main themes of the meeting to sequentially develop. The first session dealt extensively with neuro-oncology at the molecular level and included considerable discussion of material related to the babic biochemical milieu in which tumors originate, proliferate, and eventually destroy the brain. Classic neuropathology has been the mainstay of tumor identification and characteriza­ tion, however, the process of classification has become much more complex. The availability of a variety of new tools has allowed investigation into the validity of the more traditional classification systems as well as the development of newer biologically related concepts.