The present invention relates to the area of improved anti-IgE antibodies and antigen binding agents, and compositions thereof, which target IgE, for instance: for use in treating disorders caused byIgE (such as allergic responses, or certain autoimmune responses); and, in particular, disorders caused by the interaction of IgE with the Fc[epsilon]RI receptor. In particular, this invention relatesto improved anti-IgE antibodies and antigen binding agents related to novel mutants of omalizumab (Xolair). The improved anti-IgE antibodies and antigen binding agents of the invention mayhave improved affinity for IgE and/or an improved interaction with the C[epsilon]2 domain of IgE and/or an improved modified epitope on IgE (for instance further involving the C[epsilon]2 domain of IgE) and/or the ability to disassociate IgE from the Fc[epsilon]RI receptor for instance at pharmaceutically-relevant concentrations. In one aspect, improved or novel treatments for IgE mediated disorders are disclosed in which IgE is targeted (for instance free IgE and/or IgE complexed with the Fc[epsilon]RI receptor).