CT-2 mouse monoclonal antibody to the E-rosette receptor was used with complement to deplete bone marrow of E-rosette-positive cells (T cells). Depletion of E-rosette-positive cells was complete and nontoxic to hematopoietic progenitor cells. Depletion of E-rosette-positive cells with CT-2 may decrease the severity of graft-versus-host disease following bone marrow transplantation and extend the application of bone marrow transplantation to those without HLA-identical donors.