[영문]OBJECTIVE: This study examined the occurrence of medication access problems and use of intensive mental health services after the transition in January 2006 from Medicaid drug coverage to Medicare Part D for persons dually eligible for Medicaid and Medicare benefits. METHOD:S: Psychiatrists randomly selected from the American Medical Association's Physicians Masterfile reported on experiences of one systematically selected dually eligible patient (N=908) in the nine to 12 months after Part D implementation. Propensity score matching was used to compare use of psychiatric emergency department care and inpatient care between individuals who experienced a problem accessing a psychiatric medication after Part D and those who did not. RESULTS: Approximately 44% of dually eligible patients were reported to have experienced a problem accessing medications. The likelihood of visiting an emergency department was significantly higher for those who experienced an access problem than for those who did not (mean odds ratio=1.75, mean p=.003). There was no difference in number of emergency department visits or hospitalizations for those who had at least one. CONCLUSION:S: Many dually eligible patients had difficulty accessing psychiatric medications after implementation of Part D. These patients were significantly more likely to visit psychiatric emergency departments than patients who did not experience difficulties. These findings raise concerns about possible negative effects on quality of care. Additional study is needed to understand the full effects of Part D on outcomes and functioning as well as treatment costs for this population.