The spermatic cord was ligated in Charles River adult rats producing viable reversible and non viable damaged testes. Weight of the rats, weight of the testes, weight of the epididymis, sperm motility, sperm concentration and fertility were the different parameters assessed. The results showed that there is a high percentage of subsequent atrophy in the ligated testes, and that there is a definite correlation between the length of the occlusion and the amount of testicular injury sustained. Leaving a ligated testis in situ for three months provoked a severe reduction in fertility and some lesser reduction in the sperm motility in the contralateral testis. This damage was not observed in the rats where the ligated testes were removed.