Nature Neuroscience, Published online: 07 September 2026; doi:10.1038/s41593-026-02447-1 Implanted brain–computer interfaces hold great promise for restoring communication and other functions and for revealing new aspects of human brain physiology. Yet as the number of implantations in humans expands, ethical clarity must keep pace with technical ambition. We propose that this should involve distinguishing research participation from patient care, ensuring long-term support for study participants, ensuring that research participants do not bear disproportionate risks for benefits realized mainly by others, and grounding research in meaningful clinical purpose.