Background:Asthma is a chronic inflammatory disease of airways in which many cells and cellular elements play a role in particular, mast cells, eosinophils, T lymphocytes, macrophages, neutrophils and epithelial cells. Inflammation causes recurrent series of wheezing, breathlessness, chest tightness and coughing, particularly at night or in the early morning. These episodes are usually associated with widespread and variable airflow obstruction that is often reversible either spontaneously or with treatment.The inflammatory process can lead to an associated increase in bronchial hyper- responsiveness (BHR) to a variety of stimuli (e.g., allergens, respiratory viruses and some occupational exposures). Reversibility of airflow limitation may be incomplete in some asthmatic patients.Asthma is a heterogeneous disorder, with different mechanism of disease processes. Many clusters of demographics, clinical and pathophysiological characteristics are often called "asthma phenotypes"The antibronchoconstrictor efficacy of antileukotriene drugs provided the main impetus behind their introduction as the first novel class of asthma therapy in more than 20 yr. However, clinical trials also provided surprising evidence for a hitherto unsuspected role of cysteinyl-leukotrienes in promoting persistent eosinophilia in the airway and blood of patients with asthma, and possibly influencing pathways involved in airway wall remodeling. A better understanding of these actions of antileukotriene drugs will influence their place in asthma management.