Renal arteriovenous fistulas caused by vascular malformation are relatively rare, with a reported prevalence of less than 0.04%. The authors discuss about a clinical case studied by Echo-color-doppler, C.T. scan and Digital angiography. Nevertheless there is a good correlation between the results from these different Imaging Techniques, Duplex-Doppler seems to be poorly specific to define by itself a diagnosis of a tumoral renal mass.