A nation-wide survey was undertaken in Belgium among general practitioners (GPs) to evaluate the impact of the leukotriene receptor antagonist (LTRA) montelukast on the control of asthma symptoms, after at least 4 weeks of treatment. Patients from 6 years of age were eligible if they were suffering from mild-to-moderate persistent asthma which was still symptomatic despite inhaled corticosteroids (Q) treatment, or from exercise-induced asthma. Patient general satisfaction was evaluated by recording the willingness to continue the treatment. A total of 1360 GPs took part in the study and more than 11 000 patients were included in the survey. Of the included patients, 85% were receiving inhaled corticosteroids, 60% of whom were also on long-acting beta(2)-agonists (LABA). However, despite the use of daily controller medication, 92% of the patients still reported limitation of activities, 49% difficulties with sleep and 45% early morning awakening due to asthma. Moreover, 78% of the patients used rescue medication more than twice a week. At the end of the survey, 90% of the patients expressed their willingness to continue montelukast therapy. Of the patients having symptoms at the start of the study, 87% reported amelioration in sleep while on montelukast therapy, 80% less frequent early morning awakening, 85% better ability to perform daily activities and 77% decreased need for rescue medication.