Abstract: n the past two decades, pioneering research has rekindled interest in the therapeutic use of psychedelic substances such as psilocybin, ibogaine, and dimethyltryptamine (DMT). Indigenous communities have used them for centuries, and researchers studied them in the 1950s and ‘60s. However, most psychedelics were banned in the ‘70s, when President Nixon launched the U.S. war on drugs. Fifty years later, rising rates of mental illness, substance use, and suicide are prompting researchers to revisit psychedelics, and some have gained permission to study them in limited quantities. Clinical trials are producing promising results, creating enthusiasm for commercializing and patenting psychedelics. This Essay analyzes the ethical, legal, and social implications of patenting these controversial substances. Patents on psychedelics raise unique concerns associated with their unusual qualities, history, and regulation. Because they were criminalized for decades, the U.S. Patent and Trademark Office (PTO) lacks personnel with expertise in the field, rendering more questionable the quality of its evaluation of psychedelic patents. Moreover, because Indigenous communities pioneered many aspects of modern psychedelic therapies, their patenting by Western corporations may promote biopiracy, the exploitation of Indigenous knowledge without compensation. Importantly, control of psychedelics by a small number of companies may stifle innovation and reduce access to these therapies. The Essay presents proposals to reduce the risk of biopiracy and the issuance of unwarranted psychedelic patents. Potential solutions include the implementation of psychedelic patent pledges, the creation of psychedelic prior art repositories, and the tightening of patentability requirements for novel drug therapies. The Essay concludes that ultimately, due to their importance to the advancement of science and public health, it may be appropriate to view psychedelics as tools of scientific discovery, eligible only for limited patent protection.