Introduction – People with psychiatric disorders have higher mortality rates than the general population, particularly due to cardiovascular risk factors, psychotropic medications, and limited access to care. This finding suggests a higher incidence of psychiatric hospitalizations. The primary objective of this study is to describe the occurrence of serious adverse events (SAEs) during psychiatric hospitalization, defined here as unexpected deaths occurring during hospitalization and unscheduled transfers to general emergency departments.Method—A single-center, retrospective, descriptive study was conducted over a 24-month period to analyze SAEs among adults hospitalized in psychiatric facilities. Demographic characteristics, comorbidities, reasons for emergency department visits and diagnoses, iatrogenic events, and mortality at one and six months following the occurrence of the SAE were recorded.Results – A total of 144 life-threatening emergencies (6.4%) were identified, including 137 emergency transfers and 7 deaths. Life-threatening emergencies accounted for 51% of all cases, primarily due to respiratory distress. Iatrogenic causes were suspected in 41% of SAEs, and an infectious cause in 38% of cases. Twenty percent of SAEs occurred during the first 48 hours of hospitalization. The one-month mortality rate following the onset of a serious adverse event was 10% (15 out of 144 cases).Conclusion – Analysis of serious adverse events during psychiatric hospitalization helps identify areas for improvement, particularly increased monitoring during the first 48 hours and better prevention of iatrogenic events.