Abstract/Text: Operative experience with 45 gastrinoma patients has led to the identification of an anatomic area where occult tumors can be discovered and where excision of these tumors had led to apparent cure. Of 36 patients with histologically confirmed gastrinomas, 27 patients (75 percent) had obvious and 9 patients (25 percent) had occult tumors. All nine occult lesions were found within an anatomic triangle defined by the junction of the cystic and common bile ducts superiorly, the junction of the second and third portions of the duodenum inferiorly, and the junction of the neck and body of the pancreas medially. Although occult tumors from three patients (in the lymph nodes in two patients and in the duodenum in one patient) were removed primarily for histologic diagnosis, postoperative serum gastrin levels have remained within the normal range (follow-up of 86 to 99 months). Two patients had excision of the tumor with intent to cure. One patient with a solitary duodenal tumor was apparently cured but committed suicide 3 months postoperatively. The other patient had both obvious primary and occult metastatic tumors within the triangle and was eugastrinemic 9 months after excision. In all patients in whom tumor was found, it was locally excised, and no patient was subjected to radical pancreatic resection. There were no postoperative complications related to tumor removal. An aggressive approach towards curative tumor excision is now advocated for all gastrinoma patients who are suitable operative risks and have no evidence preoperatively of liver metastases or the multiple endocrine neoplasm-type I syndrome.