The results of a retrospective study of 67 patients with scrotal varicocele on the left side are presented. By means of preoperative venography of the renal, internal spermatic and common iliac veins 3 types of varicocele could be distinguished in which the cause arises in the internal spermatic vein and/or the varicocele is caused by obstruction of the common iliac vein. Use of routine preoperative venography is essential to establish the etiology of the varicocele and its proper management.