A varying percentage of cadaveric transplant recipients remain anuric or oliguric and depend on dialysis in the first weeks after transplantation. This delayed graft function group needs careful management to detect additional post-transplant events. Under these clinical circumstances, the assessment of allograft status depends to a great extent on non-invasive imaging studies. The wide variety of imaging procedures for the transplanted kidney, combined with recent technical advances in ultrasonography, scintigraphy and radiopharmaceuticals, computed tomography and magnetic resonance imaging, has created a challenging and sometimes confusing environment for clinicians, radiologists and nuclear medicine physicians. Assessing the relative merits of available procedures and choosing an optimal approach to the clinical presentation of a particular graft is sometimes difficult. The contrasting characteristics of these diagnostic methods led us to consider their relative roles and to determine their selective use. This review focuses on the value and limitations of diagnostic imaging modalities in the management of patients with impaired or delayed graft function. Our emphasis is on ultrasonography and nuclear medicine, as these are the most frequently used methods.