Gallstone disease has afflicted man since antiquity, but only in the past decade has it been recognized as a major health problem and been the subject of widespread investigation. This investiga­ tion, initiated by the definition of the limits of cholesterol solubility in bile, has led to our current understanding of the pathogenesis of gallstone formation and has provided the hasis for a rational approach to the in situ dissolution and prevention of cholesterol gallstones. This volume comprises the papers and discussion which formed the Fourth International Syrnposium of the Canadian Foundation for Diseases of the Liver. The Syrnposiurn, held in Montreal on May 12 and 13, 1978, was designed to bring together investigators from various disciplines and to review the current status of cholesterol gallstone disease. The Editors wish to thank these experts for their lucid and important contributions. We also wish to thank Valerie M. Price and Dianne McFee, of the Canadian Foundation for Diseases of the Liver, for their considerable and expert help in organizing the meeting, and preparing this volume for publication.