We assessed the effect of syngeneic and allogeneic exchange transfusion (XTF) on cell-mediated immunity in a murine burn model. Mice were given a 30% TBSA scald injury and lymphocyte function was monitored with the popliteal lymph node assay for host-versus-graft (HVG) or graft-versus-host (GVH) response. Nonexchanged burned animals exhibited suppression of GVH response on postburn days (PBD) 3 and 8 and suppression of HVG response on PBD 3, 8, 11, and 14. Syngeneic XTF stimulated GVH response on PBD 3, and significantly improved both GVH and HVG response to alloantigens on postburn days 3 and 8 compared to the response of burned controls. Allogeneic XTF significantly improved GVH response on PBD 3 and 8, but did not improve HVG response. Restoration of lymphocyte function in all experimental groups occurred between PBD 14 and 18 and coincided with wound healing.