Successful simultaneous transplants of a cancer of the ascending colon from a 60 year old woman, taken from 3 sites: the primary focus, a lymph node metastasis, and a hepatic metastasis, into nude mice yielded KHC (-P, -N, -H) strains. These three strains were compared under uniform conditions of nude mouse transplantation from the standpoints of morphological variation, growth rate, and sensitivity to chemotherapy. The results showed no major differences in morphology or growth rate. However, an effect on chemotherapeutic sensitivity was observed in KHC-P and KHC-N, with reduction rates of 25.8 per cent and 31.4 per cent, respectively, in the MMC only treatment group with large doses, and in KHC-N and KHC-H, with reduction rates of 46.5 per cent and 34.9 per cent, respectively, in the UFTM group. Chemotherapy sensitivity not only exhibited heterogeneity by site, but also differed according to the chemotherapeutic agent used. These results indicate that this method of nude mouse transplantation is a good experimental system for comparing primary foci and metastases under uniform conditions, and also strongly suggest the presence of heterogeneity in sensitivity to chemotherapy.