The invention relates to murine / human chimeric 
monoclonal antibodies with high specificity to and affinity for human 
carcinoembryonic antigen (CEA), derivatives thereof, processes for the preparation of these antibodies and their derivatives, DNAs coding for heavy and light chains of these antibodies, processes for the preparation of said DNAs, 
mammalian cell lines that produce and secrete the antibodies and processes for the preparation of said 
cell lines. The chimeric antibodies and their derivatives are used for clinical purposes 
in vitro and 
in vivo, especially for the diagnosis of 
cancer, for localization and 
in vivo imaging of tumors, for therapy, e.g. site-directed delivery of cytotoxins, and similar purposes. The invention also concerns test kits and pharmaceutical compositions containing said chimeric 
monoclonal antibodies and / or derivatives thereof.