Since more than a decade scientific and clinical interest has centered on indicator proteins, most of which have been commercialized as tumor markers. Since many of these substances are cell membrane bound, they have served also as target substances for tumor imaging with nucleide-labeled antibodies. Although this technique, which is called radio-immuno-detection (RID), has made huge progress during the last ten years, it is still not a routine procedure employable in any department of nuclear medicine. It needs experience both for the interpretation of the images and the choice of the tumors to be investigated by this method. It remains, nevertheless, that radio-immuno-scintigraphy is a simple, easy-to-handle and low-cost technique with no harmful side-effects on the patient.