Psychiatric diagnoses based on the International Classification of Diseases--Ninth Revision were examined in the medical discharge records of 33,000 emergency department (ED) patients to determine if (a) psychiatric disorders were underdiagnosed, (b) there were race and gender disparities in psychiatric rates, and (c) psychiatric rates varied as a function of type of injury (e.g., self vs. other-inflicted injuries) and medical diagnosis. The observed psychiatric rate of 5.27% was far below the national prevalence rate of 20%-28%. Both race groups were underdiagnosed, but the underdiagnosis was larger for African Americans. Younger patients had fewer psychiatric diagnoses than older patients. Men had more psychiatric diagnoses overall, whereas women had more mood and anxiety diagnoses. Self-injury patients had much higher psychiatric rates than the other injury groups. This psychiatric underdiagnosis contributes to needless emotional suffering, especially for minorities and the poor who rely on EDs for most of their health care.