When I was asked by the Cancer Teaching Committee of the University of Chicago to set up a Symposium on Brain Tumors, I welcomed the opportunity to do so. But I felt that "Brain Tumors" was far too broad a subject to cover in a day and a half meeting. Furthermore, during the past decade, there have been a great many papers and symposiums on technical advancements in the treatment of benign brain tumors. On the other hand, while gliomas make up somewhere around 50% of all brain tumors, there have certainly been far fewer communications about them. For this reason I thought that it would be highly valuable to invite some of the leading investigators to share with us their experience with gliomas. The hope was to learn the current concepts about these tumors biologically and therapeutically, specifically to find out what we are doing and where we are going in these respects. Naturally all aspects could not be covered. Nevertheless, it was a widely expressed opinion by the speakers that they too learned while they came to teach. It is therefore hoped that the publication of their works and ideas through this mono­ graph will also be useful for the reader. Most of the manu­ scripts were handed in at the time of the Symposium, and a few were sent later. Except for minor editorial changes the words are entirely those of the speakers and authors.