OBJECTIVES: The top 5% of health care users based on total expenditures [High Resource Patients (HRP)] account for roughly half of all healthcare costs. The distribution of health care expenditures for HRP is likely to differ from the overall population.  By examining spending patterns of HRP, we can better understand the components of health care expenditures that drive overall spending. METHODS: We performed a retrospective analysis of managed care enrollees across the full age and care spectrum, by examining health care claims obtained from the IMS LifeLink Health Plan Claims (HPC) Database.  A total of 15,587,257 health plan members met our selection criteria, of which 779,364 were classified as HRP.  We compared expenditures during CY2011 by place of service (Outpatient, Inpatient, Pharmacy) and payer type (Commercially insured, Medicare Advantage, and Medicaid managed care) between the full population and HRP. RESULTS: Inpatient hospitalization accounted for more direct health care expenditures for HRP (40.0%) than expenditures from pharmacy services (18.1%) or from major outpatient places of service [Ambulatory Surgical Center (ASC) 20.3%, Physician Visits (PV) 4.9%, and Emergency Department (ED) 2.7%].  The share of overall expenditures attributed to inpatient services was higher for HRP compared to the full population (24.6%) while the share of expenditures attributed to pharmacy and outpatient services was reduced (Rx: 21.4%, ASC: 19.7%, PV: 11.7%, ED: 4.5% in the full population).  This pattern was observed across payer type.  The use of physician-administered pharmaceuticals did not alter this spending pattern. CONCLUSIONS: Policy efforts to address health care cost inflation can only succeed if they address HRP, who drive overall healthcare spending disproportionately.   Understanding patterns of spending in this population can help in devising cost reduction strategies.  Policy makers should focus on integrated care for HRP, including appropriate use of pharmaceuticals, so as to potentially reduce costly downstream inpatient expenditures.