This volume comprises the proceedings of the sixth in a series of International Symposia devoted to basic and clinical aspects of urolithiasis. Previous symposia have been held at intervals of four years in Leeds, Madrid, Davos, Williamsburg, and Garmisch-Partenkirchen. The sixth symposium was held in Vancouver, British Columbia and was attended by over 250 participants from 26 countries around the world. As may be seen from the contents of this volume, the meeting covered many aspects of urolithiasis including the underlying physiology, crystal formation and the effects of inhibitors and promoters on crystallization, endocrinology and abnormalities of urinary composition, analyses, geography and epidemiology, and medical and surgical treatment with a special emphasis on extracorporeal lithotripsy. Internationally-recognized authorities gave invited talks in each of these areas, and from the submitted abstracts 30 were selected for oral presentation and the remainder were presented in either general or theme poster sessions. The nine theme-poster sessions provided a particularly valuable and successful feature of the meeting, giving an opportunity for a group of researchers working in related areas to present their posters and also to give a brief oral summary which was followed by discussion with the audience. Each of these poster sessions was chaired by two experts in the field who have provided an overview of each theme-poster session for this volume.