A comprehensive ultrasound examination of the transplanted kidney includes a Doppler examination. Duplex Doppler, color Doppler and power Doppler can all reveal important information. In addition, calculation of the resistance and pulsatility indices to quantify changes in the spectral Doppler waveform can be of great help, particularly in the first weeks and months following a transplantation. The Doppler part of the examination should evaluate the vessels to and from the transplant, as well as the parenchyma with calculations of indices to detect the presence of increased vascular resistance. The conclusions drawn from the Doppler-derived information combined with the results from gray-scale scanning and clinical information will very often be of clinical significance for the handling of the patient.