Purpose: Our study aimed to determine whether the severity of damage to the contralateral testis by ipsilateral testicular torsion/detorsion in pubertal rats, which have an incomplete blood-testis barrier, is different from that in adult rats. Materials and Methods: We divided pubertal (6 weeks, n=17) and adult (10 weeks, n=17) Sprague-Dawley (SD) rats into group S (sham; n=5), group O (orchiectomy; n=6), and group D (detorsion; n=6). After 4 hours' torsion of the ipsilateral testis, we applied orchiectomy (group O) and detorsion (group D) depending on the group and compared the histopathologic changes and germ cell apoptosis of the contralateral testis at the age of 13 weeks. Results: In each age group, increased interstitial area, edema, and germ cell sloughing were observed in group D. The mean seminiferous tubule diameter decreased more in group D than in group S or O in each age group (p<0.05). The mean germ cell layer thickness and number of spermatids per tubule decreased more in group D than in group S or O in each age group; additionally, in group D, values decreased more in pubertal rats than in adult ones (p<0.05, respectively). The mean numbers of terminal deoxyuridine nick-end labeling (TUNEL)-positive cells were less than 1.0 in groups S and O, which was smaller than in group D (p<0.05); additionally, in group D, this value tended to be higher in pubertal rats than in adult ones (p=0.057). Conclusions: SD rats with a detorsioned testis had more severe damage to the contralateral testis than did those undergoing orchiectomy of the torsioned testis. Also, when comparing the severity of damage to the contralateral testis after ipsilateral torsion/detorsion between pubertal and adult rats, rats at a pubertal age, when most testicular torsions occur in clinical situations, had more severe damage than did those at an adult age.