Asthma is a chronic inflammatory airway disorder that causes respiratory hypersensitivity and intermittent obstruction. Airway hyperresponsiveness to both specific and nonspecific stimuli is the hallmark of asthma. Although genetic susceptibility and airway inflammation are believed to play fundamental roles, etiology of asthma is unknown. In most cases, the treatment of asthma focuses on control of factors contributing to asthma severity and pharmacologic therapy including bronchodilator and anti-inflammatory agents. The prevalence of reported asthma is greater in prepubertal boys, with a change to a female predominance after puberty. Many epidemiological studies also suggest that women are at increased risk of developing adult-onset asthma and also suffer from more severe disease than men. This strongly suggests an important role for sex hormones in asthma. Previous articles provided us that, testosterone and/or its metabolites maintain the physiological balance of autoimmunity and protective immunity by preserving the number of regulatory cells. Testosterone is an immunosuppressant and is likely to be protective against immunological and inflammatory processes that trigger asthma. We hypothesized that the testosterone or selective androgen receptor modulators would have beneficial effects on asthma and could decrease the risk of asthmatic attacks.