Utilizing the fluorescence-activated cell sorter (FACS) and washed murine antibody-antigen complexes formed in antibody excess, we have demonstrated the presence of the Fc receptor on the surface of a distinct subpopulation of murine T lymphocytes. No differences in intensity of labeling with the complexes was observed when the Fc+ T lymphocytes were compared with Fc+ B lymphocytes. The majority of Fc+ T lymphocytes are small lymphocytes determined by light-scattering characteristics on the FACS. Separating Fc+ from Fc- T lymphocytes from spleens of mice primed 1 wk or 1 mo previously with keyhole limpet hemocyanin (KLH) revealed that the T cells capable of cooperating with DNP-KLH primed B cells to give an adoptive anti-DNP PFC response do not bear the Fc receptor.