The primary as well as an ongoing IgE response to the haptens--2,4-dinitrophenyl (DNP) and benzylpénicilloyl (BPO) determinants--were readily abrogated in an immunologically specific manner by the administration of conjugates consisting of the corresponding hapten coupled to the isologous, non-immunogenic murine gamma globulins (MgammaG), i. e., DNP8-MgammaG or BPO9-MgammaG. The epitope density of the DNPx-MgammaG and BPOx-MgammaG was shown to play a dominant role in determining whether or not these conjugates were tolerogenic. Using the adoptive transfer system in mice, it was demonstrated that this method of immunosuppression was not due to the formation of suppressor cells, but involved the elimination of hapten specific IgE-forming Bepsilon cells or the inactivation of these cells through the blockade of their antigen binding receptors. This method of suppression of anti-hapten IgE antibodies, by the use of conjugates of haptens with isologous gamma-globulins, proved also effective in rats and dogs.