Background: Poor asthma control observed in several surveys may be related to a lack of systematic assessment by physicians and/or to patient underestimation of symptoms. Along this line, the purpose of this study was to investigate the level of asthma control in patients attending the GP office for different reasons, either for renewal of drug prescription or for worsening of asthma symptoms. Methods: Each of the 145 General Practitioners (GP) in Italy and Spain selected at least eight asthmatic patients attending their office for a renewal of drug prescription (Group A) or for worsening of asthma symptoms (Group B), between May and December 2009. Asthma Control Test (ACT) and other clinical information (including SF-12 questionnaire) were collected. Results: Data from 1375 patients with moderate-severe asthma were analysed (mean age: 47.2 years; female: 59%; smokers or ex-smokers: 35.4%); 57% were on treatment with ICS-LABA combination. ACT score < 20 (uncontrolled asthma) was observed in 77.8% Group B patients, as expected, but also in 28.6% Group A patients. Uncontrolled patients reported their asthma being well or fairly well controlled in 68.4% of cases. Risk factors for uncontrolled asthma were older age, asthma severity, and smoking habit. In uncontrolled patients, GPs changed or increased the level of therapy in 75.8% and initiated asthma treatment in 61.3% of cases, in association with educational intervention, closer monitoring or pulmonologist consultations. Discussion: The systematic use of ACT in asthmatics attending GP's clinic may detect high rates of uncontrolled patients who underestimate their clinical conditions, particularly those asking solely for asthma medication renewal. Poor adherence to daily drug therapy was reported in more than 40% of patients and could be an important contributor of uncontrolled asthma. Conclusions: The results highlight the importance of routine longitudinal assessment of asthma patients in primary care and point to the need for an increased attention to asthma management by GPs.