This Thesis analyses the effect of add-on mepolizumab therapy compared to the traditional therapy plan for patients with severe eosinophilic asthma bronchiale. Mepolizumab is an Anti-Interleukin 5 (Anti IL-5) Antibody. From the Department of Pulmonology, University of Debrecen, 13 patients were investigated. Eosinophil cell count, tiffeneau index (FEV1%), Quality-of-Life as well as oral corticosteroid requirement and number of acute exacerbations were compared. Mepolizumab showed significant benefits compared to traditional therapy alone.