Allogeneic hematopoietic stem cell transplantation (HSCT) has been restricted to medically fit patients under the age of 55 years due to adverse effects of the intensive conditioning regimens. Autologous HSCT has not proven to be a particularly effective treatment for patients with low-grade non-Hodgkin's lymphoma (NHL). Much of the benefit of allogeneic HSCT appears to be mediated by a graft-vs.-tumor (GVT) effect. Reduced-intensity regimens in allogeneic HSCT have been developed to minimize conditioning regimen-related toxicities and to control the malignancy until a GVT effect is established. A number of studies investigating reduced-intensity allogeneic HSCT are discussed. Results from these studies suggest that indications for allogeneic transplant include patients with low-grade NHL with a sibling or matched donor who are under 60 years of age; young patients with mantle cell lymphoma who are in first remission and have a sibling or matched donor; patients with high-grade NHL who have already failed an autograft but have chemosensitive disease, and those under 30 years of age who have poor-risk disease and are in first remission. It is concluded that reduction in treatment-related mortality with reduced-intensity HSCT and the presence of GVT effects increases the applicability of allogeneic transplantation for NHL. However, treatment will be improved by optimizating conditioning regimens and a better understanding of patient selection criteria and the immune processes involved in graft-vs.-host disease and GVT.