Procedures for successful autologous and MHC-matched allogeneic bone marrow transplantation in partially inbred, MHC-defined miniature swine have been established. All marrow recipients were conditioned with single-dose total-body irradiation at the upper level of tolerance, and supported with antibiotics and irradiated blood products during aplasia. Surgical harvest of autologous and allogeneic marrow yielded sufficient numbers of cells to successfully reocnstitute recipients. Radiation control animals that reveived no marrow failed to show recovery of marrow function. Pigs transplanted with autologous marrow at dosed greater than10 8 cells/kg/routinely engrafted and recovered normal marrow function. The major clinical complications were acute and chronic infections and hemorrhage. T cell-depleted autologous marrow also engrafted, and there was no observed increase in clinical complications. In bone marrow transplantation across non-MHC allogeneic differences, engraftment and survival were similar