Allogeneic hematopoietic stem cell transplantation after reduced-intensity conditioning (RIC-allo) is an option for patients relapsing after autologous SCT, allowing long-term progression free survival of 50 to 60%. The toxic mortality related to severe acute graft versus host disease (GVHD) remains a critical issue. The goal of our study is to test in a multicentric approach a strategy of RIC-allo including rituximab in order to reduce the incidence of acute GVHD.