Better understanding of the cellular and molecular mechanisms of asthma have made it possible to envision a large number of new treatment targets. Clinical trials assessing some of these targets were recently published. The results of these trials were often disappointing. For example, parenteral administration of anti-interleukin-5 antibodies diminished bronchial eosinophilic inflammation but without improving either asthma symptoms or bronchial hyperreactivity. Other treatments are promising but have not yet been proved effective in patients with asthma: open studies with anti-TNF alpha antibodies are interesting but the efficacy of this treatment strategy remains uncertain and must be validated against placebo. The first targeted treatment approved for severe difficult-to-control allergic asthma is an anti-IgE monoclonal antibody (omalizumab).