One-hundred-fifteen allografts of the distal canine stomach were studied. The mean survival times were: 5.1 days in untreated hosts; 5.8 days in hosts that had undergone previous exchange blood transfusion with the donor; 3.2 days in dogs undergoing attempts at immunologic enhancement; and 14.9 days in dogs receiving immunosuppressive drugs (azathioprine, Actinomycin C, and prednisolone). Allografts placed into animals that had acted as hosts to previous gastric transplants did not survive as long as those placed into virgin hosts. Transplanted fundic pouches secreted acid normally except during periods of rejection. Secretion returned to normal after successful drug treatment of threatened rejection. Fundic allografts released gastrin following stimulation. Fundic allografts secreted acid in response to endogeous gastrin from both autogenous and allografted antra, as well as in response to exogenous gastrin and histamine. The gastric allograft provides valuable information in the study of mechanisms of gastric secretion.