Chimeras have been an important part of animal research for decades. Yet crossing the species barrier has always been seen as potentially morally problematic. In recent years, advances in chimeric research and the attendant possibilities—organ xenotransplantation, cognitive enhancement, and others—have given rise to further ethical concern. This contribution surveys the main ethical questions that have been discussed in the literature. We examine two arguments—from the order of nature and from human dignity—which aim to show that chimerization is inherently wrong. Finding the first untenable and the second largely inapplicable, we then turn to two unconvincing arguments designed to show that chimerization must necessarily lead to negative outcomes. Having thus found that no blanket statements can be made on the ethics of chimerization, we examine two important parameters relevant to the ethical evaluation of proposed chimeric research: The argument from moral status and from risk.