In recent years, interest in psychedelics and their possible benefit in treating psychiatric illnesses has been revived. Expectations are high, especially in obsessive-compulsive disorder, where patients’ therapeutic options are still limited. At Paris Brain Institute, Anne Buot, Luc Mallet (AP-HP), and their colleagues are gathering evidence that could pave the way for large-scale clinical trials. In a new study published in Scientific Reports, they show that LSD and psilocybin have strong potential for providing long-lasting relief of patients’ symptoms.