OBJECTIVE To evaluate the effect of taurine, a potent antioxidant, on testicular ischemia-reperfusion injury due to excess reactive oxygen species produced by neutrophils after testicular torsion-detorsion. METHODS A total of 60 adult male Sprague-Dawley rats were randomly divided into three groups, each containing 20 rats. The control group underwent a sham operation of the left testis. In the torsion-detorsion group, the left testis was rotated 720 degrees counterclockwise for 2 hours. The treatment group underwent the same surgical procedure as the torsion-detorsion group, but taurine was administered intravenously at repair of the testicular torsion. One half of the rats in each group underwent orchiectomy 4 hours after detorsion for measurement of myeloperoxidase activity, an indicator of neutrophil accumulation in the testis, and for evaluation of tissue malondialdehyde, an indicator of intratesticular reactive oxygen species content. The remainder were killed at orchiectomy 3 months after detorsion for analysis of testicular spermatogenesis. RESULTS Unilateral testicular torsion-detorsion caused a significant increase in myeloperoxidase activity and the malondialdehyde level and a significant decrease in testicular spermatogenesis in the ipsilateral testes. The decrease in ipsilateral testicular spermatogenesis involved a reduction in testicular weight, mean seminiferous tubular diameter, number of germ cell layers, and mean testicular biopsy score. The rats treated with taurine had a significant decrease in myeloperoxidase activity and malondialdehyde level and a significant increase in testicular spermatogenesis in the ipsilateral testes compared with the torsion-detorsion group. CONCLUSIONS The results of our study have shown that the administration of taurine exerts a beneficial effect on testicular ischemia-reperfusion injury. This effect might be partly the result of a reduction in reactive oxygen species generation by diminishing neutrophil recruitment to the testis.