A total of 77 patients with advanced colorectal cancer, including postoperative patients with liver, lung and peritoneal metastases, were treated with single or multiple injections of monoclonal antibody A7-neocarzinostatin (A7-NCS). A follow-up study of the patients treated with A7-NCS was done and the clinical outcome was compared with that of patients given other chemotherapies. In the postoperative patients with liver metastasis, the A7-NCS treatment prolonged survival time when compared with systemic administration of anticancer drugs, while it showed a similar survival time to chemoembolization using multiple anticancer agents suspended in a lipid contrast medium. Among the patients who underwent surgical resection of primary cancer, with or without liver metastasis, there was no difference in overall 5-year survival rate between the group treated with A7-NCS and the group treated with the other chemotherapies. However, the survival time of the patients treated with A7-NCS was longer than that of the patients treated with the other chemotherapies. In addition, the patients given a higher dose of A7-NCS had a longer survival time than the patients given a lower dose of A7-NCS. Human anti-mouse antibody was detected in all the A7-NCS-treated patients examined. There were no serious side effects in any of the patients given A7-NCS. Thus, this study indicates that the A7-NCS treatment is safe and useful for colorectal cancer patients, though some problems remain, such as optimization of injection dose, route, interval, etc., and overcoming human anti-mouse antibody development.