Oxygen free radicals generated during the ischemic/reperfusion period have been suggested as a possible cause for tissue damage in different organs. In this study we address the question of whether administration of polyethylene glycol-superoxide dismutase, an oxygen free radical scavenger, can alleviate histological damage associated with testicular torsion. The study included 67 Sprague-Dawley rats. In 60 rats the left testicle was rotated 720 degrees clockwise through a scrotal incision. Torsion duration was 3 hours. Five minutes before and 5 minutes after detorsion the testicle color was evaluated and scored. The remaining 7 rats underwent a sham operation. After randomization 8,000 units per kg. polyethylene glycol-superoxide dismutase were injected intraperitoneally in the treated group 1 hour before detorsion. After 14 days histological evaluation was performed on both testicles of 58 rats (2 rats died before the evaluation). No statistically significant difference was demonstrated between the treatment (28 rats) and the control groups (30 rats). Testicular color after detorsion correlated with the histological damage.