A rounded shadow of the renal sinus was observed, during the late vascular period of intravenous urography, in a true profile film of the kidney. Interpreted as being due to an aneurysm, a series of investigations were instituted, including more particularly angiography. It was finally demonstrated that the image corresponded to the segment of origin of a rectiliniar renal vein, seen axially. An observation of this type has not been previously reported, and raises certain questions on the practical attitude to adopt in such cases.