OBJECTIVE: To investigate the antioxidant effects of an AT1 receptor blocker losartan on the apoptosis of spermatogenic cells in torsion/detorsion damage in rats using the TUNEL assay method. STUDY DESIGN: Forty male Wistar albino rats were categorized into 4 groups. For Group 1 (sham group), only the abdominal wall was opened and closed. In Group 2 (torsion group), the left testis was rotated 720° degrees clockwise around the longitudinal axis of the spermatic cord for 2.5 hours. For Group 3 (torsion/ detorsion), after 2.5 hours of the torsion process, a suture that fixed the testis to the tunica dartos was cut off for detorsion for the following 3 hours. In Group 4 (torsion/detorsion+losartan), 2.5 hours of ischemia was followed by administration of 40 mg/kg losartan 30 minutes prior to a 3-hour detorsion/reperfusion. Biochemical assays (MDA, SOD, CAT, and GSH levels) and his-topathologic results were examined in testicular tissue. The TUNEL assay method was used for DNA fragmentation analysis in testicular seminiferous tubule sections. RESULTS: Losartan treatment seemed to prevent the increase in MDA levels of torsion/detorsion–induced testis. Statistically, SOD, CAT, and GSH activities were significantly decreased in the torsion/detorsion group, while they were increased in the torsion/detorsion+ losartan group. Testicular tubule diameter measurements were evaluated between groups. In the torsion and torsion/detorsion group, degeneration and loss in the germ cells together with organization disorder were observed. In the losartan application, degenerative changes were decreased and tubular structure was preserved. In the torsion and torsion/detorsion groups, an increase in apoptosis was observed in the germ cells in the tubules, and it was observed that the application of losartan decreased germ cell apoptosis. CONCLUSION: The experimental testis torsion/detorsion study suggests a protective role for losartan upon ischemia and ischemia/reperfusion injury in rat testes. © 2020 Science Printers and Publishers Inc.. All rights reserved.