Unilateral testicular trauma in the postpubertal male can lead to alterations in semen analysis, but it is not clear what effect this has on fertility. To better understand how surgical treatment of testicular trauma affects both fertility and testicular histology the following study was performed. Eighty postpubertal Lewis rats were divided into eight equal groups with one group serving as a control. In the 70 remaining rats the left testicle was subjected to blunt or penetrating injury. The testicles were either left untreated, were removed, or were repaired with sutures or mesh before being returned to the scrotum. Following recovery, each male was allowed to mate to determine fertility. Fertility rates were significantly lower in all postinjury groups except the postinjury orchiectomy group. Histological analyses showed nonspecific inflammation, smaller tubules, and impaired spermatogenesis in all postinjury testicles regardless of the type of treatment. Contralateral testicles had no evidence of autoimmune injury and were essentially identical to the control group. In the postpubertal Lewis rat, unilateral testicular trauma leads to impaired fertility unless the injured testicle is removed soon after the injury. Various methods of repairing the injury did not improve fertility. In spite of the impaired fertility, the contralateral testicle appears histologically normal.