This study examines the ethical permissibility of biomedical moral enhancement (BME) for psychopaths, considering both coercive and voluntary approaches. To do so, I will first briefly explain what psychopaths are and some normative implications of these facts. I will then ethically examine three scenarios of BME for psychopaths: (1) coercive BME for non-criminal psychopaths, (2) coercive BME for psychopathic offenders, and (3) voluntary BME for psychopathic offenders. I will argue that coercive BME for non-criminal psychopaths is ethically problematic due to issues of cost, invasion of privacy, and stigmatic effects of compulsory diagnosis. Similarly, I will argue that coercive BME for criminals is impermissible due to violations of the rights to bodily and mental integrity. However, I will show that voluntary BME for offenders may be ethically permissible under certain conditions, challenging the critique that the consent of vulnerable prisoners cannot be considered fully voluntary. I argue that when an offender is provided with sufficient medical and legal information, incentives such as the possibility of parole review based on BME results do not preclude the voluntariness of consent. Ultimately, I aim to advance the debate on BME for psychopaths by delineating and defending conditions for the ethical permissibility of voluntary BME.