Asthma is a common chronic inflammatory disease of the airways of the lungs, in the world. It’s associated with type 2 cytokines interleukin-4, IL-5, and IL-13, which promote airway eosinophilia, bronchial hyperresponsiveness, mucus overproduction, and immunogloubulin E synthesis. IL-5 is a cytokine known to play major role in the regulation of eosinophil formation, maturation, survival, and recruitment. Hence, an increased production of IL-5 may be contributed to the pathogenesis of asthma. The expression of human IL-5 receptor presented on eosinophils, basophils, and mast cells. Hence, a polymorphism in IL-5 receptor may be implicated in the development of asthma. Many candidate genes that could potentially contribute to the susceptibility to the disease have not been investigated to date, and not all of the polymorphisms of the candidate genes have been tested for a possible association with the disease. Taking this into consideration, IL-5 (together with the IL-5 receptor) polymorphism deserves attention as the subject of further investigations into asthma. In this review, we will address the role of IL-5 and IL-5 receptor polymorphism in asthma, describe the impact of these polymorphisms on the Blood parameters and clinical parameters. Further, give an overview of preclinical and clinical studies targeting the IL-5 and IL-5 receptor pathway.