The objectives of this article were to estimate the prevalence of asthma control and describe the characteristics of at least well-controlled (ALWC) versus not well-controlled (NWC) asthmatics. Data were obtained from the European National Health and Wellness Survey, an internet-based, cross-sectional study of 37,476 adults in France, Germany, Italy, Spain and the UK. Analysis was limited to 2,337 respondents who self-reported a physician diagnosis. Based on the Asthma Control Test (ACT), respondents were grouped as ALWC (ACT ≥20) and NWC (ACT ≤19). The prevalence of diagnosed asthma across five countries was estimated to be 5.8% (14 million extrapolated for the European Union population). Of these, 50.4% (7.1 million) were NWC. Compared with ALWC, NWC were older (15.8 versus 15.0%; p<0.001), less likely to be college educated (28.7 versus 36.3%; p<0.001) and more likely to be obese (30.0 versus 22.7%; p<0.001), experience depression (28.0 versus 18.7%; p<0.001) and smoke (34.7 versus 25.0%; p<0.001). The NWC had more occasions of contact with healthcare providers and were more likely to use controller and rescue medications, but with less adherence. A substantial portion of asthmatics are NWC. However, the proportion of NWC asthmatics found in this study was less than in previously reported. Patients and physicians need to be educated on the importance of asthma control and adherence to treatments.