OBJECTIVES: Current asthma management recommendations are based on the level of asthma control rather than disease severity. The financial impact associated with asthma control needs to be determined. The primary objective of this study was to estimate quality of life and health care costs according to the patients’ level of asthma control in France and in Spain. METHODS: An observational retrospective bottom-up cost of illness study was conducted in adults patients with asthma. Investigators were general practitioners. Asthma control was evaluated using the validated auto-test Asthma Control Test (ACTTM) for a one month period and 2009 GINA’s asthma control criteria for a three months period. Quality of life (QoL) was assessed using EQ-5D profile. Costs (direct and indirect) were evaluated from a societal perspective. RESULTS: 794 patients (France: 391; Spain: 403) were enrolled in the first quarterly wave of the survey. Based on the ACT, asthma was determined to be well-controlled (ACT ≥ 20) in 48.1% [IC 95%: 42.1% - 54%] and 56.2% [IC95: 51.1% - 61.2%] of French and Spanish patients respectively. In both countries, EQ-5D scores were 0.9 and 0.7 in well-controlled and not well-controlled patients respectively (p<0.0001). Total costs of asthma were directly related to asthma control in both countries. The average cost (Euros/month/patient) of well-controlled asthma was €28  (±36) in France and €77  (±105) in Spain compared with €140  (±782) (p=0.0009) and €252  (±380) (p <0.0001) respectively for not well-controlled asthma. Similar associations were observed using the latest GINA’s criteria. CONCLUSIONS: We found strong associations between asthma control level, costs and QoL in patients with asthma. Achievement of good clinical control of asthma may result in a significant decrease of the economic burden of asthma and a better health status in adults.