This chapter is designed to provide a scientist who is not familiar with the brain slice preparation with some of the information needed to evaluate its suitability for a particular task. It is obviously not possible in a book chapter to describe all the uses to which brain slices have been put, and so one is faced with the options of describing one’s own studies, embroidered perhaps by those of others when necessary, of lighting on specific topics and hoping that these will satisfy some of the readers, or, as I have chosen to do, of trying to evaluate the suitability of the slice preparation for as wide a variety of uses as possible None of these approaches can be completely satisfactory. I chose the latter because, ultimately, we must determine the applicability of information we get from the slice to events in the intact brain This, of course, is true for all model systems, but seems particularly urgent for brain studies in which the difficulty of studying the intact organ has led to an abundance of model systems and in which the tissue is so fragile It thus seems important not only to describe, but also evaluate different ways of preparing and experimenting on tissue, even if such an evaluation must be subjective