Introduction: The structure called the residual gubernaculum (G) has been evaluated to define its origin. Materials and Methods: Girls operated for inguinal hernia (n = 7) and boys operated for undescended testis (n = 12), inguinal hernia (n = 7), hydrocele of the cord (n = 1), and ectopic (n = 1) and entrapped (n = 1) testes were evaluated. Attachments of the structures coursing distally from the sacs were identified, and they were removed en block. Three samples, first from the distal part of the sac with the beginning of the fibrous structure, second from the midportion, and third from the most distal part, were prepared and stained with hematoxylin-eosin, trichrome and elastic van Gieson. Histologic structures within the samples were determined and compared with Mann-Whitney U test. Results and Conclusions: Structures called the residual G differed from the walls of accompanying sacs by only the absence of mesothelial lining. Therefore, the structure called the residual G in boys with an undescended testis and the round ligament in girls actually represent the obliterated processus vaginalis. Copyright (C) 2002 S. Karger AG, Basel.