Radiolabeling of antibodies with In-111 has now been accomplished to the point that it is highly reproducible, achieves excellent labeling efficiency, and does not damage the antibody. Use of In-111 for radioimmunodetection is advantageous because of the excellent imaging characteristics of the In-111, moderate radiation dose, ease of labeling, and appropriate half-life. The liabilities of the In-111 method include slightly greater cost of the radionuclide, slow clearance of background sites, and a shelf life requiring it to be ordered on a weekly basis. When all characteristics of the radionuclide are taken into account, it appears to be superior to I-131 for radioimmunoimaging. A controlled study using iodinated and Indium labeled antibodies in the same group of patients needs to be done to accurately access how well the two function for tumor detection.