The anticancer activity of KW2149, a new derivative of mitomycin C (MMC), was investigated against 5 human tumor xenografts derived from digestive organs using 4-day subrenal capsule assay (SRCA). Normal immunocompetent mice were used in this assay. For the comparative study, KW 2149 and MMC were administered intraperitoneally for 3 days after implantation, and the anticancer activity and the weight loss of mice were evaluated. The total doses were determined as 1/2, 1/3 and 1/4 of LD50 value of each anticancer agent. The anticancer activities of the two drugs were almost the same with no significant difference in 3 xenografts. Thus, it may be suggested the difference of the anticancer spectrum between the two drugs. The anticancer activity of KW2149 indicated higher correlation with the administered doses as compared with MMC. The toxicity of KW2149 was almost the same as MMC according to the weight loss of mice.