Not long ago it was customary to expect an atmosphere of confrontation and controversy when urologic surgeons and infectious disease physicians met at conferences and symposia. Even more often each group exhibited an attitude of "benign neglect" towards the other. Times have changed in large part because of the efforts of the leadership group in urology. The establishment of an Advisory Board for this Journal, drawn from non-urological disciplines, is one example of the effort being made to draw together all concerned with urinary tract infections and pyelonephritis. I have been asked to review some practical up-to-date matters relating to the diagnosis and treatment of urinary tract infections and pyelonephritis from the point of view of an infectious disease physician. However, it may be helpful to begin with a synthesis of current concepts of the natural history of urinary tract infection, since the need for early diagnosis and the tactics for treatment depend largely on our expectations for the patient. This synthesis requires definition of terms that are acceptable to a wide variety of disciplines. The review would then focus on new methods for screening and office diagnosis, antimicrobial sensitivity tests, localization of infection and indications for urologic investigation, particularly in relation to vesicoureteral reflux. New developments in treatment of urinary tract infections will be discussed. Special attention will be given to areas in which we are ignorant and require more information. Last, I will direct my attention to the problem of the urinary catheter, hoping to arrive at a synthesis of the situation which will tell it like it is but avoid overstating the case.