Five lymphoma patients relapsed from allogeneic hematopoietic stem cell transplantation (HSCT). Three patients who received myeloablative conditioning had full donor chimerism at relapse, whereas two who received nonmyeloablative conditioning had partially or completely lost the graft. All received mini-BEAM [carmustine (BCNU), etoposide, cytarabine (AraC), melphalan], followed by infusion of HSC (four peripheral blood, one marrow) from the initial donor. Neutropenia and thrombocytopenia were brief, and full donor chimerism was established in all cases. There were four complete and one partial remissions. Graft-versus-host disease occurred in three cases, all with full donor chimerism at relapse. Two patients died subsequently of disease relapse or progression. Another two patients died from fungal infection, one of whom was still in remission at death. One patient had remained in remission 47 months after treatment. Mini-BEAM/HSC is an effective treatment for lymphoma relapses after allogeneic HSCT, but optimal strategies of remission consolidation and prevention of treatment-related complications are needed to improve outcome.