<imgsrc=”” border=”0″ align=”left” alt=”image”>Some patients engage in self-harm behaviors while in the emergency department. Risk factors for self-harm have been described for inpatient and outpatient/community settings, but not among emergency department patients. Authors conducted case-control, retrospective reviews of medical records and incident reports for emergency department patients in two academic medical centers. Variables were analyzed using conditional logistic regression. There were 113 individuals who engaged in self-harm while in the emergency department and 226 individuals who did not. Four variables were significant in the final model: a history of nonsuicidal self-harm (odds ratio [OR], 4.28; 95% confidence interval [CI], 1.95–9.41), opioid use in the prior 2 weeks (OR, 2.89; CI, 1.19–7.02), current manic episode (OR, 3.59; CI, 1.33–9.70), and a history of seizures (OR, 4.19; CI, 1.16–15.14). Risk of self-harm while in the emergency department may be mitigated with interventions that support adaptive coping skills, promptly address pain and withdrawal symptoms, and treat mania.