When Critical Issues in Psychiatry was conceived, there were several sub jects I considered to be of crucial importance in a series devoted to residents and clinicians in psychiatry, as well as to other mental health professionals. Of prominence was the pressing need for an in-depth and scholarly exam ination of the interface between medicine and psychiatry. I had been amazed to find that not a single book, to my mind, adequately addressed the psy chological symptoms and manifestations of both common and rare medical illness. It seemed to me that there was a need for a work which would achieve the following goals: First, it would assist in the differential diagnosis of functional psychiatric symptoms versus symptoms secondary to recog nized or unrecognized medical illness; second, it would elucidate the psy chological symptoms resulting from pharmacologic and other therapeutic interventions in medical illness; and third, it would examine the use of psychopharmacological agents in the presence of medical illness and the drugs used to treat that illness. Dr. Jefferson is Board Certified in both internal medicine and psychiatry, and both Drs. Jefferson and Marshall have extensive clinical experience from their many years of consultation/liaison work in psychiatry. Their experience and expertise have resulted in what I believe to be a monumental contri bution to the literature.