Selective retrograde catheterisation of the left internal spermatic vein at its orifice in the renal vein was carried out in 25 patients suspected of varicocele. When contrast medium is injected, the patients with varicocele, standing in the erect position, present a retrograde filling of the varicose spermatic vein, in contrast to the absence of such reflux in normal men. The venography is indicated for diagnostic and therapeutic purposes and it is the only available, non-surgical technique to prove the existence of a disturbed venous flow in the testicular region.