Monoclonal antibodies against IgE immunoglobulins are a novel class of antiasthmatic agents. The use of these agents is based upon the evidence that IgE is involved in the mechanisms of airways inflammation and, consequently, in clinical symptoms of asthma. Newly published data indicate a athophysiologic role of localy released IgE in the airways of non allergic asthmatic patients. RhuMAb-25 monoclonal antibodies are binded to the high affinity receptors of IgE, on the membrane of mast cells and baseophils. Therefore, they block the IgE-mediated mechanisms of asthmatic airways inflammation. They decrease the levels of free IgE, as well as the expression of IgE receptors on pro-inflammatory cells. The up today clinical studies of the drug indicate a good therapeutic potency primarily in patients with allergic asthma, either adults or children. Pneumon 2001, 14(3):206-216.