There is no doubt that the poor reputation of T-cell depleted bone marrow transplant arises from its use in CML patients, where an increase in graft rejection and, above all, in leukaemia relapse has been reported by almost all centres. Evidence suggests that the standard conditioning regimen (once thought to be sufficiently immunosuppressive and myeloablative in unmanipulated transplants) should no longer be considered adequate when the immunological balance has shifted in favour of unopposed host-versus-graft reactivity and the GvL effect is lacking. Since GvHD remains the major problem in BMT, we suggest T-cell depletion should be considered the most effective method for GvHD prophylaxis but the cytoreductive effect of the conditioning regimens and the anti-leukaemia immune reactivity should be enhanced.