The antigen-reactive cells in normal rabbit bone marrow could be isolated from a suspension of marrow cells by passage of the cells through an antigen-sensitized glass bead column. The cells which passed through the column were deficient in antigen-reactive cells directed to the antigen used to sensitize the glass beads, whereas the cells eluted from the column could transfer antibody-forming capacity to irradiated recipients only with respect to the specific sensitizing antigen. Separation of the bone marrow antigen-reactive cells could not be achieved by passage of the cells through nonsensitized glass bead columns or in the presence of excess free antigen in the column. Cells which were retained by, and later eluted from, the antigen-sensitized glass bead columns were mostly small mononuclear cells, whereas cells which passed through the columns were morphologically similar to the original unfractionated bone marrow cell suspension. The data indicate the presence of an antibody or antibody-like structure, with defined immunological specificity, on the surface of the normal bone marrow antigen-reactive cell.