Artery stenosis in the transplanted kidney is the most frequent vascular complication; hypertension onset or worsening may be associated and, at an end stage, also renal insufficiency. The diagnosis must be early and accurate and provide guidelines for medical, interventional or surgical therapy. To assess the diagnostic reliability or MRA, 27 patients were examined. On the basis of clinical, biochemical, pharmacological (Captopril test) and instrumental (color-Doppler US) examinations, the artery of the transplanted kidney was considered normal in 6 patients and stenotic in 21. In the control group, MRA results were in agreement with color-Doppler findings. On the contrary, in 8 of 21 abnormal conditions, the two techniques were in disagreement. Digital angiography, considered as the gold standard, was performed in any questionable case, confirming a slight overestimation of the stenoses by MRA (3 cases) and 2 false positives by color-Doppler US. The authors believe color-Doppler US to be a reliable technique for screening stenosed arteries in the transplanted kidney. MRA is proposed as a complementary investigation useful to define stenosis type and to provide guidelines for treatment.