OBJECTIVES: We sought to estimate clinical and demographic predictors of inpatient admission following an opioid abuse-related emergency department (ED) visit in the United States. METHODS: Data for these analyses were derived from the 2006 - 2008 Healthcare Cost and Utilization Project’s Nationwide Emergency Departments Sample (HCUP-NEDS). We identified events and charges assigned opioid abuse, dependence, or poisoning ICD-9-CM codes – 304.0X, 304.7X, 305.5X, 965.00, 965.02, and 965.09. Logistic regression was used to compute the likelihood of inpatient admission in the same hospital following an opioid abuse-related ED visit, adjusting for age, gender, patient residence county classification, US Census region, primary payer, number of comorbidities, presence of specific comorbidity groups (e.g., liver disease, heart disease, etc.), and income quartile for ZIP code. RESULTS: After adjusting for geographic location and specific comorbidities, factors that were significantly (p <0.01) positively associated with the likelihood of inpatient admission include: number of comorbidities (OR=1.68; 95% CI: 1.63-1.73); privately insured (OR=1.15; 95% CI: 1.05-1.25) and patients covered by other payers (like Worker’s Compensation, CHAMPUS, CHAMPVA, Title V) (OR=1.67; 95% CI: 1.43-1.95) as compared to Medicare patients. Factors that were significantly (p <0.01) negatively associated with the likelihood of inpatient admission include: increasing age (OR=0.996; 95% CI: 0.994-0.998); being female (OR=0.83; 95% CI: 0.79-0.87); being uninsured (self-pay) as compared to being covered by Medicare (OR=0.79; 95% CI: 0.69-0.89). CONCLUSIONS: These data provide evidence that comorbid conditions contribute substantially to the likelihood of inpatient admission following ED visit for opioid abuse or misuse. Emphasizing appropriate use of opioid medications may help reduce the clinical and economic burden due to adverse events in the setting of appropriate use.