The authors reviewed the results of their research on the structure and composition of normal and varicocele seminiferous tubules in adolescents. They give new evidences of normal structure of adolescent testis and demonstrate, for the first time, the ultrastructural and immunohistochemical modifications of the lamina propria and basal lamina in the adolescent varicocele patients, which are similar to those observed in adults, but less severe, and of the adherence junctions in seminiferous tubules. They also report the presence of oxidative stress in adolescents limited to testis and not generalised as in the adults. These data are well correlated to different clinical studies that support the hypothesis of a progressive course of varicocele and the need for surgical treatment in adolescent varicocele patients.