The authors present two cases of gastrin-producing carcinoma demonstrated by scintigraphy with In-111 pentetreotide. The possible malignant evolution of such tumours and the good results that can be achieved with surgical therapy suggest the usefulness of a radio-guided intraoperative strategy to locate the lesions and minimise invasive procedures. This approach enabled us to detect a lymph-node metastasis concealed in the adipose tissue in the first case and to exclude any other gastrin-producing tumour localisations in the second. We recommend that the radio-guided strategy should be included among the guidelines for the treatment of gastrinomas and believe that the procedure can also be used in other functioning endocrine tumours.