A retrospective analysis of 177 retrograde venographies of the left renal and gonadal veins was made. Renal venography seems a useful investigation in cases of male infertility without clinically palpable variococele. Selective venography of the internal spermatic vein seems of little value, as it may give false positive ("iatrogenic") spermatic venous reflux. This can be explained by passing the catheter over a competent valve. After operation for subclinical varicocele, the spermiogram does not change, but a pregnancy rate of 30% is obtained. These results are analogous to those obtained in an operated group of clinical varicoceles.