OBJECTIVES: Emergency room (ER) visits are perceived with the high costs and unpredictable outcomes.  Although the association between Attention Deficit Hyperactivity Disorder (ADHD), stimulants and ER visits has been studied; difference between the types of stimulants in terms of risk of ER visits have not been studied. Our objective is to identify the difference between the effects of long acting and short acting stimulant use in ADHD on ER visits in 18 to 35 year old adults (n=636) in the year 2011. METHODS: This retrospective secondary data analysis used the Medical Expenditure Panel Survey (MEPS) data for the year 2011. Univariate and Multivariate logistic regression were used to evaluate risk factors influencing type of stimulant use on ER visits. Risk factor and stimulant interactions were also included. RESULTS: The risk of ER visits in long acting stimulant users, among the uninsured, on adjusting for race, marital and insurance status,  is 14.25 times (p=0.001) the risk of ER visits in short acting stimulant users. If they are insured, the risk of ER visits in long acting stimulant users is 1.83 times the risk of ER visits in short acting stimulant users (p=0.26). CONCLUSIONS: Long-acting stimulants combined with lack of insurance is a risk factor for increased ER visits.  Our results support Affordable Care Act’s efforts for the requirements of expansion on coverage in mental disorders to reach better healthcare outcome.