This volume comprises the proceedings of the sixth International Symposium on Drugs Affecting Lipid Meta bolism. Since the first of these symposia in 1960 these triennial meetings have been devoted to the exploration of new ideas, new data and new concepts related to lipid metabolism and atherosclerosis. The sixth Meeting was particularly stimulating in this regard. The concept of the "protective" action of HDL was thoroughly explored within the framework of its molecular biology with data on its epidemiological as well as its in vitro mechan ism(s) of action being discussed. The action of drugs on arterial and HDL metabolism was also discussed as were newer aspects of platelet aggregation, especially as related to prostaglandins. New ground was also broken in discussions of lipid mobilization and mechan isms of hypocholesteremia. We are indebted to the many organizations who con tributed generously to the support of this meeting. Among the sponsors, the assistance of the Lorenzini Foundation was especially helpful. As in all meetings of this type, the hard work of the local organizing committee was instrumental in its success. We are grateful to Mrs. Caroline Hyatt and Mr. Ralph Hollerorth for their invaluable help in the secretariat. We are also deeply indebted to Miss Jane T. Kolimaga for her expert assistance in the preparation of this volume. David Kritchevsky Rodolfo Paoletti William L. Holmes vii Contents LIPOPROTEINS AND DRUGS Lipoprotein Metabolism - New Insights from Cell Biology. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 D. Steinberg Lipoprotein Metabolism in Man. . . . . . . . . . . . . . . . . . . .