Biomedical enhancement interventions to make people stronger, smarter, and happier are currently being developed. Research to assess these enhancements should be conducted before their introduction into clinical practice. But, many worry that enhancement research is unethical. Some contend that the practice of biomedical enhancements is unethical; accordingly, research that enables such practice would be unethical. Others suggest that research on enhancement interventions does not promote health, exposing research participants to risks with no potential compensating health benefits either to themselves or to society. Categorically condemning research on biomedical enhancements as unethical is unwarranted, however, since at least some research on biomedical enhancements is likely to produce significant health benefits. Indeed, under certain circumstances enhancement research would be urgent, as it would address major public health concerns. Therefore, a blanket prohibition on enhancement research is unjustified. Instead, like any other clinical research, each proposed enhancement study should be reviewed individually to assess whether it fulfills the ethical requirements that make a clinical study permissible.