OBJECTIVE The incidence of arterial hypertension post-renal transplantation has been reported to be 48.6%. The present study investigated the usefulness of echo Doppler in detecting renal artery stenosis and the effects of arterial pressure control and hypotensive agents on the vascular resistance of the renal graft. METHODS A total of 234 echo Doppler studies were done in 110 patients. The pulsatility index (PI), resistance index (RI), acceleration and mean velocity (MV), maximum systolic (SVMX) and minimum diastolic (DVMN) velocities of the external iliac, renal, segmental, interlobar and arcuate arteries were determined. RESULTS In the stenotic segment, an elevation of SVMX was observed, followed by turbulent flow in the post-stenotic segment in 73% of the cases with arterial stenosis. The hypertensive patients had a higher external iliac artery RI than the normotensives. The beta-blockers reduced the RI in large vessels (external iliac), the vasodilators in medium-sized extraparenchymal vessels (segmental) and the calcium antagonists changed the PI in the smaller caliber intraparenchymal vessels (interlobar and arcuate). CONCLUSIONS Evaluation by echo Doppler is the first diagnostic approach in patients suspected as having arterial stenosis of the renal graft. It permits evaluating blood flow changes from hypertension and hypotensive agents.