A total of 33 specimens of human gastric carcinoma were used for transplantation into nude mice. Initital tumor "take" was accomplished in 15 of the 33 tumors, and the transplantability rate was 45.5%. Transplantability correlated with histologic type, but not with clinical stage or Borrmann's classification. The transplantability rate of differentiated carcinomas, such as well-differentiated tubular adenocarcinoma, moderately differentiated tubular adenocarcinoma, and papillary adenocarcinoma was greater than that of poorly differentiated tumors, such as poorly differentiated adenocarcinoma and mucinous adenocarcinoma. The growth patterns of transplanted tumors were divided into 3 types: rapid, slow, and persistent. There were no specific relationships between growth pattern and histologic type. All histologic types, except signet ring cell carcinoma, could be transplanted serially. Tumor growth became rapid after serial transfer. However, the original histology of these tumors was unchanged. No invasion or metastases were encountered. Intraperitoneal injection of a tumor cell suspension, prepared from subcutaneous transplants of a poorly differentiated adenocarcinoma of Borrmann type III, grew in an ascites form, with invasion and metastasis. Ascitic fluid accumulated within 3--6 weeks after injection. Subsequently, intravenous injection of ascites fluid produced metastases in nude mice. The histology of the subcutaneous tumor was similar to that of the original tumor from the patient.