The advent in recent years of several new imaging modalities for the application in diag nosis and patient management has had an unprecedented impact on patient care. By per mitting the acquisition of information without intervention, these new modalities have made the diagnostic process more humane. They have also made possible the treatment of many disorders of the upper and lower urinary tract by means of interventional tech niques, replacing a number of surgical procedures. The editor of this volume has engaged international experts in radiology to describe the state of the art of radio log y of the upper urinary tract. Local and regional abnormalities are covered, but so too is the involvement of urinary structures in systemic disease. The radiologic approach and interpretation are combined with the presentation of pertinent clinical observations and important pathophysiologic concepts. The text is concise and the illustrations are appropriate. Up-to-date international bibliographies are provided. Both the text and the illustrations will serve as sources of information for the radiologists, urol ogists, nephrologists, gynecologists, and oncologists. Most importantly, the material is presented in such a way that practicing specialists dealing with urologic disorders, as well as physicians in training will benefit. We feel that it is timely to publish a present day treatise on urinary tract radiology in order to convey the contributions made by various newer imaging modalities to the diagnosis of urinary disorders.