Monoclonal antibodies (McAbs) were prepared against carcinoembryonic antigen (CEA), derived from human metastases to the liver of primary colon adenocarcinoma. A stable clone, secreting monoclonal anti-CEA antibody (Ab), was selected. The hybridoma cells were grown in BALB/C mice, forming ascites fluids containing 2-5 mg/ml of the relevant McAbs. Ascites fluids were purified using a DEAE-Sephacel column. The purified immunoglobulin fraction was characterized as IgG2b, having a dissociation constant of 2 X 10(-9)M. The potential use of these McAbs for CEA diagnosis and purification was evaluated: the IgG2b fraction, when bound to Sepharose 4B, facilitated the purification of CEA from spent media of a human colon adenocarcinoma cell line, resulting in iodination grade CEA; the anti-CEA McAbs demonstrated differential histochemical staining of various sections, both fresh and fixed; the McAbs were also found to be suitable as tagging Abs in a CEA RIA.