Fertility potential in patients with unilateral (UL) undescended testis is a debated topic. An experimental study was done in rats by surgically creating a UL undescended testis and studying its effect on their potential to father offspring when housed with female rats. No difference in fertility potential was observed in the various groups in this study. Since fertility was tested immediately after the rats became mature, it could be possible that fertility might decrease if the rats were tested in later adulthood. We conclude that experimentally created UL undescended testis does not cause damage sufficient to result in infertility in young adult rats. Also discussed is the significance of this finding in relation to UL undescended testis in humans.