Asthma is a pathophysiological condition associated with eosinophilia and heightened inflammatory reactions, epithelial desquamation, hyper responsiveness, recurring episodes of reversible broncho-constriction, and mucus hyper secretion from the respiratory organs. Asthma interludes can be triggered by a variety of factors most notably allergens, infectious agents, pollutants, and nonspecific stimuli such as exercise, nutritional factors and emotional stress. Certain genes and their polymorphism may also have effects in the initiation and progression of asthma. Thus asthma may also be classified as atopic (extrinsic) or non-atopic (intrinsic). Here atopy refers to a predisposition towards developing type 1 hypersensitivity reactions. In a present day scenario asthma is termed as a complex genetic disorder with a heterogeneous phenotype, largely attributed to the interactions between genes and/or environment. Hence, pharmacogenomics is an important area to understand the influence of genetic variations on drug response in asthmatics by correlating gene expression or single-nucleotide polymorphisms (SNPs) with drug's efficacy. This article reviews the role of various genes and their polymorphism in initiation, complication of asthma and its treatment strategies focussing on disease causing polymorphic and novel genes.