It has often surprised me that in order to study the subject of obstructive uropathy, it is necessary to search through various sections of several urological, surgical and radiological textbooks rather than turn to one work on the subject. It is also true that, even now, many descriptions tend to concentrate on the causative conditions rather than their relationship to the proximal outflow tract, in a way which is predominantly structural and anatomical rather than functional and urodynamic. The subject of obstructive uropathy has changed radically in recent years. Inspired research from several centres has given us great insight into the mechanisms of obstruction and its effects on the outflow tract and nephron. It has been accompanied by the development of new methods of investigation in both the experimental and the clinical field. This book is an attempt to update and distill the subject of obstructive uropathy in one volume. For the purpose of the work, obstructive uropathy is taken to include any condition involving the outflow tract of the kidney, from minor calyces to urethra, which results in obstruction to the flow of urine. Emphasis is on physiology and pathophysiol­ ogy, function and urodynamics. These considerations should not be thought of as purely theoretical. Far from it. They hold the key to subsequent decisions on diagnosis and management and form the basis for a practical approach to the patient with obstruction. The only details the reader will not find here are descriptions of surgical technique.