This review aims to evaluate the efficacy of the leukotriene modifiers in the different stages and subgroups of asthma. In mild asthma, they bring some improvement as monotherapy, but less than inhaled steroids. In moderate asthma, leukotriene modifiers associated with inhaled steroids seem to offer a slight advantage over placebo. No evidence of additional effect has been published in severe asthma. Exercice- and aspirin-induced asthma are particulary responsive to leukotriene modifiers. This treatment may also play a role in acute asthma. In practice, it is possible to select patients who benefit from those molecules. If only these "responders" are treated, leukotriene modifiers are an adequate treatment, easy to use and well tolerated.