Nuclear medicine techniques for evaluating the kidney and urinary tract have evolved from pioneering studies with primitive radiopharmaceuticals and hand-held probe detectors to a sophisticated technology capable of providing important physiologic and anatomic information. Advances in nuclear medicine and computer technology over the past decade have resulted in improved, clinically useful scintigraphic studies to assist clinicians in examining patients who have diseases of the genitourinary tract. However, renal scintigraphy is a complex subject. Five different radiopharmaceuticals are available for scanning the kidneys, multiple quantitative indexes can be generated, and protocols may vary depending on the clinical setting. The focus of this review is practical: to summarize the clinical advantages and disadvantages of the different radiopharmaceuticals; to review quantitative indexes that help interpret images; and to review the role of radionuclide scintigraphy in patients with suspected obstruction, pyelonephritis, and renovascular hypertension.