Xolair is a monoclonal antibody that binds the C epsilon 3 domain of IgEs, inducing a conformational change of the immunoglobulin, a concealment of Fc epsilon RI and Fc epsilon RII receptors binding sites, thus precluding binding by IgEs and therefore stopping the release of inflammation mediators. Xolair is indicated as add-on therapy to improve/control asthma in adult and adolescent patients (12 years of age and above) suffering from severe persistent allergic asthma. The aim of our work was to evaluate the Xolair efficacy in the asthma treatment. Six patients (4 men and 2 women aged 30 to 60 years) were selected for the treatment with Xolair. Previously, they were treated with high doses of long-acting beta 2-agonists and inhaled corticosteroids, but they were not able to control their illness despite the assumption of such drugs. Xolair was administered for 32 weeks in addition to the traditional asthma therapy. Xolair dosage was calculated according to their weight and their IgE levels (IU/ml). The therapeutic response was evaluated according to the GETE (Global Evaluation of Treatment Effectiveness) scale. The persistence of the response was defined, instead, by the number of patients continuing to respond positively to the treatment between the 16(th) and the 32(nd) week. 4 of 6 patients concluded the study. Patient number 2, in fact, had a body weight higher than 150 kg, so it was impossible to establish the necessary drug dosage. Patient number 6, instead, still had too high IgE values at his fourth checkup. Patient number 1 was fit in the efficacy level 2 (Good) at the 16(th) week, while at the 32(nd) week, he was in the level 1 (Excellent). Patient number 3 was at an efficacy level 1 yet from the 16(th) week, and that level was confirmed at the 32(nd). In patient number 4, as well in that number 1, an increase of treatment efficacy was proved with a passage from level 2 to level 1. Finally, for the patient number 5, the efficacy level was Good both at the 16(th) and at the 32(nd) week (level 2). The results obtained were positive for all patients and not only the persistence of a therapeutic response was confirmed, but in some cases there was an improvement of efficacy. Therefore, we can conclude that Xolair, administrated as an additional therapy, strongly improved the severe persistent IgE-mediated asthma. The anti-IgE Xolair treatment reduces the asthma frequency, also, it improved the patient life quality, by inducing positive effects on symptoms and pulmonary function.