Healthcare costs were determined for mild persistent asthma patients (n=796) who used inhaled corticosteroids infrequently (0 to 2 claims) or consistently (3 or more claims). Study patients, selected from a privately insured claims database (1999-2003), had at least one asthma diagnosis, no diagnosis of chronic obstructive pulmonary disease (COPD), and mild persistent asthma as defined by the 2005 Health Plan Employer Data and Information Set (HEDIS), Leidy's reliever and oral steroid methods, and the 2004 Global Initiative for Asthma (GINA) guidelines. Healthcare and asthma-specific costs were significantly higher for the infrequent inhaled corticosteroid users than the consistent users. The infrequent inhaled corticosteroid users had significantly more hospitalizations and emergency department visits compared with consistent users.