Nonhuman primates are the closest relatives to humans and therefore our most evolutionary close cousins. While marvelous insights are gleaned from studying rodents and other systems, it is impossible to envision how those mechanistic findings can be responsibly translated to the clinic without the appropriate use of nonhuman primates. Thankfully, noninvasive technologies now permit nonhuman primate studies without endangering the model itself. Work with primates is predicted to continue to lead the fields of reproductive and regenerative medicine for the rest of the twenty-first century.