Intraoperative radioimmunolocalization is a potentially useful technique for staging gastric neoplasms without resorting to extensive surgical intervention. Before preoperative immunohistochemical typing for the presence or absence of tumor-associated glycoprotein (TAG) 72, we performed intraoperative radioimmunodetection on three patients presenting with gastric carcinoma using a whole monoclonal antibody (B72.3) marked with Indium-111 injected 1 week before operation. The results were calculated on the number of lymph node stations and yielded a high sensitivity due to a specificity of 72% and the absence of false negatives. Intraoperative radioimmunolocalization is a promising method for noninvasive staging of both early and advanced gastric carcinoma.