Unilateral torsion of the testis was experimentally induced in Sprague-Dowley rats by an incision in the scrotum and manual rotation of the testis. The testes remained torted for 3 or 24 hours and then were released by detorsion or orchiectomy. Histologic changes were evaluated 2 weeks and 4 weeks post torsion episode in order to answer the following questions:(1) Does the duration of testicular torsion affect the degree of histologic change in the contralateral testis? (2) Does the treatment of the torted testis influence the contralateral testis histologically? (3) Are there any histologic differences according to the duration of the follow-up in each group? The results indicate that when a torted testis was kept in place for at least 24 hrs, then was a marked decrease in spermatogenesis, but even this histologic change disappeared 4 weeks later. In conclusion a torted testis may present a liability to the patient's contralateral testis, but this phenomena is temporal.