Various preparations of anti-CEA antibodies have shown to detect very sensitively CEA producing tumors. The development of human anti-mouse antibodies (HAMA) prevents from the widespread use of immunoscintigraphy (IS) in the follow-up of patients with colorectal carcinoma. It is, however, not yet clear if genetically reshaped antibodies will solve this problem and it is even less clear if this will change prognosis of these patients. There is certainly room for new therapeutic approaches in colorectal carcinoma. Radioimmunotherapy in combination with other techniques might advantageously complete surgery, chemotherapy and radiotherapy, but needs to be further developed.