In this article the authors analyze in detail the clinical role of immunoglobulins E and eosinophils in the etiology and pathogenesis of asthma, and their impact on the course of asthma. They discuss problems related to the treatment of severe bronchial asthma and new therapeutic options. They recall the positions of experts on the criteria for qualifying for biological therapies and discuss the order of drug use, especially in the group of patients presenting simultaneously the phenotype of allergic and eosinophilic asthma.