This monograph was developed from a collection of papers that were origi nally presented at a symposium entitled Pathogenesis of Hypertension held at the Henry Chauncy Conference Center, Princeton. New Jersey. These manuscripts were subsequently revised, updated, and reorganized in a manner suitable for this publication. The symposium was planned to stimu late interest among investigators and clinicians alike in the potential for a new class of drugs called converting enzyme inhibitors in clinical medicine. The meeting was sponsored by the Squibb Institute for Medical Research, whose pioneering biochemical and pharmaceutical research had led to the development of the first orally active converting enzyme inhibitor. It is hoped that this monograph will cohesively pull together the thesis that the identification, quantification, and containment of the renin factor in hypertension can be a powerful diagnostic and therapeutic strategy in clinical medicine. In addition, the sequence of studies presented in this manuscript will serve to demonstrate how basic biochemical and physio logical research produces fundamental and critical information on which subsequent major advances in clinical pharmacology and medicine can be based.