We evaluated the usefulness of in vitro human tumor culture system using a specialized collagen gel matrix derived from pigskin as a chemosensitivity test for human gastric cancer including scirrhous type. Seven xenograft tumors derived from human gastric cancers were examined with this system and compared with the data obtained by the nude mouse chemosensitivity assay. Xenograft tumors exhibited an in vivo like three-dimensional growth on the collagen gel matrix. There were very close associations between the results obtained by this assay and those obtained from the same drug by the nude mouse assay. Moreover, this system seemed to be useful for prediction of drug sensitivity for scirrhous type gastric cancers. This in vitro assay system has an advantage for chemosensitivity test, because of its convenience, rapidity, and in vivo like three-dimensional tumor growth.