Seventeen dogs with spontaneous generalized lymphoma in complete clinical remission induced with combination chemotherapy were given 1100 R total body irradiation (TBI) and autologous marrow grafts as consolidation therapy. Marrow was obtained immediately before TBI, stored at 4 degrees C, and infused immediately after TBI. Two dogs died because of failure to regain adequate marrow function, 8 died after developing recurrent lymphoma and 2 died of miscellaneous causes. Five dogs are alive in unmaintained complete clinical remission 200-663 days after initiation of chemotherapy. In a comparable group of 8 dogs in complete remission after combination chemotherapy but not given consolidation therapy, none remained in remission beyond 113 days. These results indicate that high dose TBI in conjunction with autologous marrow grafting results in prolonged remission duration in dogs with spontaneous lymphoma.