When my colleagues and I began the task of assembling this volume, several difficult questions arose: For whom were we writing? Was the purpose to eluci­ date psychiatric or medical presentation? Should references reflect specific to­ pical areas, or lead the reader to a more general view of a particular topic? Would a symptom or system approach best serve the reader? Should the volume cover a few areas in detail, or attempt to survey a larger area of knowledge? The present text reflects an attempt to answer these questions. It is designed for the student of medicine who desires a broader understanding of those medi­ cal illnesses that produce psychiatric aberration. We hope it will be of assis­ tance to the medical student or house officer studying medicine, neurology, family practice, pediatrics, or psychiatry; as well as to the practicing clinician who wishes a refresher on this subject or a reference for his library. The text is intended to strike a useful balance between medicine and psychiatry by provid­ ing a list of differentials for specific symptoms or conditions, as well as sugges­ tions for medical evaluation. References have been chosen which we hope will assist the reader in further study. We have attempted to diversify them and list a spectrum of articles that deal with both academic and practical treatment considerations. The initial volume is divided into four sections that address both a symptom and system approach.