Optimal conditions were established for the adoptive transfer of experimental allergic encephalomyelitis (EAE) in SJL/J mice. Lymph node cells from SJL/J mice primed in vivo with myelin basic protein (BP) were incubated in vitro with BP. These cells proliferated specifically to BP and when transferred at the optimal conditions into syngeneic mice induced EAE in 100% of the recipients. The in vitro proliferative response to BP was dependent on the presence of Lyt 1+ 2- T lymphocytes. Furthermore, when the activated LNC were treated before transfer with anti-Thy 1 or anti-Lyt 1 antibody and C, neither clinical nor histologic signs were observed in the recipients, whereas treatment with anti-Lyt 2 antibody and C had no effect. These results indicated that Lyt 1+ 2- T cells are responsible for the transfer of EAE.