Modern antiretroviral therapies (ART) are capable of suppressing HIV in the bloodstream to undetectable levels. Nonetheless, people living with HIV must maintain lifelong adherence to ART to avoid the re-emergence of the infection. So despite the existence and efficacy of ART, there is still substantial interest in development of a cure. But HIV cure trials can be risky, their success is as of yet unlikely, and the medical gain of being cured is limited against a baseline of ART access. The medical prospect associated with participation in cure research thus look poor. Are the risks and burdens that HIV cure research places on participants so high that it is unethical, at present, to conduct it? In this paper, I answer 'no'. I start my argument by describing a foundational way of thinking about the ethical justification for regulatory limits on research risk; I then apply this way of thinking to HIV cure trials. In offering this analysis, I confine my attention to studies enrolling competent adults and I also do not consider risks research may pose to third parties or society. Rather, my concern is to engage with the thought that some trials are so risky that performing them is an ethically unacceptable way to treat the participants themselves. I reject this thought and instead argue that there is no level of risk, no matter how high, that inherently mistreats a participant.