Asthma is a chronic inflammatory disorder of the lungs and has a significant impact on morbidity, mortality, and health-related quality of life (HRQL). Asthma also impacts indirect costs resulting from losses in workplace productivity. OBJECTIVE: To examine the association of medication adherence with workplace productivity and HRQL in patients with asthma in a state health insurance program. METHODS: The diagnosis of asthma was identified from medical claims data of state employees between 18 and 65 years of age who obtained healthcare benefits from a state health insurance program from July 2001 through June 2003. A three-part survey was mailed to these patients to measure HRQL, workplace productivity, (absenteeism[time lost from work] and presenteeism [reduced productivity at work]), and self-reported medication adherence. The survey consisted of the St. George's Respiratory Questionnaire, the Workplace Productivity Short Inventory, and the Morisky Adherence Scale. Productivity losses were translated into dollar values by using previously published metrics (employer perspective). The association between self-reported medication adherence and HRQL and productivity was measured using multivariate regression analyses. RESULTS: The response rate was 25.1% (385/1,493). The mean HRQL total summary score was 33.2 ± 19.9 units, with the symptoms domain having the worst HRQL scores (49.3 ± 21.4 units), followed by the activity (39.6 ± 26.6) and impacts (24.6 ± 19.1) domains. 39% of the participants reported themselves as ‘high' adherent, 19% reported themselves as ‘medium' adherent, and 42% as ‘low' adherent. Asthma resulted in productivity losses of $597 ± $1024 (absenteeism) and $658 ± $1808 (presenteeism) per enrollee per year. Morisky-based adherence was not a significant predictor of HRQL or productivity in the multivariate models. CONCLUSIONS: Asthma was associated with HRQL detriments and workplace productivity losses. Medication adherence continues to be a problem among asthma patients.