The coexistence of psychiatric symptomatology among individuals receiving longer-term treatment for alcohol use disorders has been well-established; however, less is known about comorbidity among individuals receiving alcohol detoxification. Using the Brief Symptom Inventory [BSI; Derogatis, L. R. (1992). BSI: Administration, scoring, and procedures manual--II. Towson, MD: Clinical Psychometric Research], we compared psychiatric symptomatology among 815 individuals receiving short-term detoxification services with normative data from non-patients, psychiatric patients, and out-of-treatment individuals using street drugs. Findings revealed that individuals in the current sample reported a wide range of psychiatric symptoms with over 80% meeting BSI criteria for diagnosable mental illness. These BSI scores were significantly more severe than those reported by out-of-treatment individuals using street drugs and most closely resembled BSI scores reported for adult psychiatric inpatients. Findings suggest that routine screening for severe mental health symptoms appears warranted in detoxification units. Such screening would greatly increase the chance that coexistence of substance use and other psychiatric disorders would be properly addressed in ongoing treatment.