Unilateral spermatic cord torsion in the presence or absence of ipsilateral testis causes hypoxia in the contralateral testis. An experimental study was conducted to find the most important structure that causes contralateral testicular hypoxia following ipsilateral twisting. In five groups each consisting of 10 rats sham operations, epididymoorchiectomy, spermatic cord torsion, spermatic cord torsion following subepididymal orchiectomy or spermatic cord torsion following epididymoorchiectomy were performed. Lactic acid, hypoxanthine and thiobarbituric acid reactive products of lipid peroxidation (TEAR) were determined in the contralateral testis While lactic acid, hypoxanthine and TEAR values did not differ significantly following sham and epididymoorchiectomy procedures, evaluation of other groups revealed significantly increased values compared with sham and epididymoorchiectomy groups. Since torsion of only spermatic cord and testicular vasculature causes contralateral testicular hypoxia, testis and epididymis do not seem to be mandatory for occurrence Of contralateral testicular hypoxia. Testicular artery under distress seems to be the most important structure that results in contralateral testicular hypoxia following torsion.