ABSTRACT: Use of classic psychedelics (e.g., psilocybin, ayahuasca, and lysergic acid diethylamide) is increasing, and psychedelic therapy is receiving growing attention as a novel mental health intervention. Suicidality remains a potential safety concern associated with classic psychedelics and is, concurrently, a mental health concern that psychedelic therapy may show promise in targeting. Accordingly, further understanding of the relationship between classic psychedelics and suicidality is needed. Therefore, we conducted a systematic review of the relationship between classic psychedelics (both non-clinical psychedelic use and psychedelic therapy) and suicidality. We identified a total of 64 articles, including 41 articles on the association between nonclinical classic psychedelic use and suicidality and 23 articles on the effects of psychedelic therapy on suicidality. Findings on the association between lifetime classic psychedelic use and suicidality were mixed, with studies finding positive, negative, and no significant association. A small number of reports of suicide and decreased suicidality following non-clinical classic psychedelic use were identified. Several cases of suicide in early psychedelic therapy were identified; however, it was unclear whether this was due to psychedelic therapy itself. In recent psychedelic therapy clinical trials, we found no reports of increased suicidality and preliminary evidence for acute and sustained decreases in suicidality following treatment. We identify some remaining questions and provide suggestions for future research on the association between classic psychedelics and suicidality.