In patients with undescended testes the demonstration of the pampiniform plexus (i.e. venous network surrounding the testis) by selective retrograde contrast filling of the internal spermatic vein gives exact information about the existence and localization of the gonadal tissue. Especially with small hypoplastic testes and/or an intraabdominal position of the gonad the results of this technique are superior to those of ultrasound and computed tomography. The venographic information often helps to reduce the extent of the surgical exploration, most of all in those cases in which after an ineffective first procedure a second operation is planned. Venography can be done on an outpatient basis in children from an age of about 6 years upwards without general anesthesia and serious complications. Personal experiences with the spermatic venography in 11 patients (age: 7-32 years) with 18 undescended testes are demonstrated. Comparing the roentgenologic and surgical findings in 7 patients with 12 explored veins the results corresponded completely in 75%. In the remaining cases roentgenologic demonstration of one of the testicular veins with its pampinifom plexus suggested important information about the localization of the contralateral testis, surgically confirmed later.