The contents of this volume reflect the foresightedness of our former Editor, the late Dr. Henry W. Elliott. The chapters on opiate receptors and endogenous peptides and analgesia are topics of continuous, increasing interest. The volume also contains several reviews on some aspects of chemical pharmacology, another reflection of Dr. Elliott's desire to expand the scope of Annual Review of Pharmacology and Toxicology. Dr. Elliott would have been pleased with the appointment of our new Associate Editor, Dr. Arthur K. Cho, Professor of Pharmacology, UCLA School of Medicine, who brings expertise in the area of chemical pharmacology. The Editors have had a long association with Dr. Cho and know that he will be a tremendous asset to the Editorial Board.

Finally, our sincere thanks to Production Editor, Toni Haskell, and Indexers, Dorothy Read and Mary Glass.

The Editorial Committee