Background: There is an increasing use of ayahuasca for recreational purposes. Furthermore, there is a growing evidence for the antidepressant properties of its components. However, there are no reports on the effects of this substance in the psychiatric setting. Harmaline, one of the main components of ayahuasca, is a selective and reversible MAO-A inhibitor and a serotonin reuptake inhibitor. Case report: We present the case of a man with bipolar disorder who had a manic episode after an ayahuasca consumption ritual. This patient had had at least one hypomanic episode in the past and is currently depressed. We discuss the diagnostic repercussion of this manic episode. Conclusion: There is lack of specificity in the diagnosis of substance-induced mental disorder. The knowledge of the pharmacodynamic properties of ayahuasca consumption allows a more physiopathological approach to the diagnosis of the patient. Keywords: Ayahuasca; Bipolar disorder; DSM 5; Switch to mania; MAO inhibitors