Most men who have a testicle removed are still able to have children. You have two testicles. The remaining one can usually still make sperm. However, many men who have testicular tumors, even when the tumor is removed, have sperm counts that aren't quite as fertile as men who never had a testicular tumor. It's not so much that the removal of the testicle compromises fertility, but that whatever caused the testicular cancer, genetically, tends to lead to poorer quality sperm counts.
