A new cell line (RCN-9) was established in culture from a transplantable rat colon adenocarcinoma, which was induced in the colon of a male Fischer F344 rat by subcutaneous administration of 1,2-dimethylhydrazine. When RCN-9 cells were injected subcutaneously or into the cecal subserosa of syngeneic rats, carcinomas with progressive growth were obtained and the development of lung (63.6%) and liver (40.0%) metastases, respectively, ensued. Antitumor effects of 5-fluorouracil (5-FU), adriamycin (ADM) and mitomycin C (MMC) against RCN-9 were examined in vivo and in vitro. 5-FU and ADM had antitumor effects both in vivo and in vitro; MMC had antitumor effects in vitro. These results show that the RCN-9 cell line can be used both as a model to study mechanisms of metastasis from colon carcinoma and as a model in chemotherapeutic studies of metastatic disease from colon carcinoma.