Localization of IgG, IgA and IgM in human palatine tonsils, especially in germinal centers, was studied with the electron microscopical enzyme‐labeled antibody method. The large germinal center cells differentiate into two kinds of cells within the germinal center; one was the medium‐sized germinal center cells not engaging in intracytoplasmic production of immunoglobulins and another was the immature cells producing at least one of the three classes of immunoglobulins, especially IgM. The latter continued to maturate and developed into the intermediate‐matured cells and probably into the plasmocytes. The three classes of immunoglobulins were also deposited in the form of admixtures in the intercellular spaces among the constituent cells of the germinal centers, mainly attaching on the cell membrane of desmo‐dendric cells. In addition, some of the deposits were found freely in the intercellular spaces. Some demureness between the immunoglobulin‐containing cells outside and within the germinal centers were po