BAT monoclonal antibody exhibited anti-tumor activity mediated by T and NK cells. We have evaluated the efficacy of murine and humanized BAT for the treatment of human colorectal carcinoma liver metastases in nude mice. HM7, a human colorectal carcinoma was injected into the spleen to colonize the liver. A single intravenous administration of both BAT antibodies significantly reduced the number of metastases and liver weights. Histological examinations demonstrated lymphocyte accumulation near remnant tumors and in tumor-free tissues of BAT treated mice. The efficacy of humanized BAT in the regression of hepatic metastases in human colorectal carcinoma has potential clinical use.