by E.K. ZSIGMOND, M.D. Department of Anesthesiology University of Illinois Chicago U.S.A. It is, indeed, a distinct honor and privilege to be invited by the authors to write a preface to this monumental monograph, Regional Opioid Analgesia. Regional Opioid Analgesia is a colossal undertaking by Drs. De Castro, Meynadier and Zenz shortly after the introduction of this revolutionary approach to pain relief which opened a new epoch in analgesiology. This is, indeed, the first authentic and comprehensive textbook encompassing the current knowl edge on this novel approach to pain relief. We are indebted to the authors for introducing the new opioids to regional analgesia with the scientists, who de veloped the potent short and ultrashort acting opioids with high therapeutic indices, which many researchers dreamt about but never before materialized. The side effect liabilities of these new opioids are minute as compared to morphine and meperidine. Regional Opioid Analgesia could not have been more authentically written than by Drs. De Castro,Zenz and Meynadier,who have conducted daily clinical investigations on all known opioids for regional analgesia as well as for neurolept analgesia. Therein lies the great value of this monograph: it is the most authentic work on this topic.