As a general term, pharmacogenetics identifies the genetic determinants underlying a response to a pharmacological agent. Pharmacogenetics may regulate the relationship between the pharmacological agent and the host response in a variety of ways. In order for a drug target to be a candidate for pharmacogenetic associations, there should be variability among members of a population in the treatment response observed with a given treatment. This means that, for a given treatment, there should be some patients who respond well and some who respond poorly. Another prerequisite for pharmacogenetic associations is the repeatability of a response. Repeatability identifies the consistency of a response. In other words, for a given treatment the response remains the same, either poor or favorable, throughout different time points. Although there are data on the variability of the treatment response to all classes of medications that are used in the treatment of asthma i.e. glucocorticoids, theophylline, ß₂ agonists and leukotriene modifiers, pharmacogenetic associations have been described for ß₂ agonists, leukotriene modifiers and very recently for corticosteroids. This review will focus on recent studies that investigate the pharmacogenetics of ß₂ agonists, leukotriene modifiers and corticosteroids. Anahtar Kelimeler : farmakogenetik, glukokortikoid, ß₂ agonistler ve anti-lökotrienler,pharmacogenetics, glucocorticoids, ß₂ agonists, leukotriene modifiers.