OBJECTIVES: Severe, poorly-controlled asthma affects a minority of asthma patients but accounts for a disproportionately large amount of asthma-related medical expenditures. Based on 2007 NIH (NHLBI EPR-3) guidelines, oral corticosteroids (OCS) are recommended therapy for step 6 management of severe persistent asthma. We sought to better understand asthma-related health care utilization in patients who require frequent OCS.   METHODS: We examined Thomson Reuters MarketScan claims data (2006-2010) to identify patients aged ≥12 years, continuously enrolled for ≥24 months, with OCS-dependent asthma, defined as ≥3 30-day OCS fills over a 12-month period and a primary asthma diagnosis (ICD-9 493) within 12 months of the first OCS fill. Excluded were patients with COPD including emphysema, cystic fibrosis, acute respiratory failure, and 29 other conditions that may require frequent OCS. Asthma-related health care utilization was examined during the 12-month period following patients’ first OCS fill. RESULTS: Among the 10,319 patients meeting study criteria, 6,941 (67.3%) were female; the mean (SD) age at first OCS fill was 57.9 (15.9). The most common comorbid diagnoses were allergic rhinitis (n=1,507; 14.6%), chronic sinusitis (n=1,236; 12.0%), pneumonia (n=1,066; 10.4%), and gastroesophageal reflux disease (n=1,036; 10.0%). During 12-month follow-up, patients received a mean (SD) of 6.2 (3.6) OCS fills. OCS was used in conjunction with at least 2 additional asthma medications in 6,671 (64.6%) patients, but only 5,428 (52.6%) received concomitant guideline-recommended treatment with both an inhaled corticosteroid and long-acting beta agonist. Asthma-related hospitalizations and emergency department (ED) visits were experienced by 6.5% (n=673) and 6.9% (n=712) of patients, respectively. The mean (SD) number of asthma-related hospitalizations was 1.4 (1.5), with an average stay of 4.6 days; the mean (SD) number of asthma-related ED visits was 1.2 (0.5). CONCLUSIONS: Despite frequent use of OCS and additional asthma medications, this population of patients with asthma experienced high levels of asthma-related hospitalizations and ED visits.