Operative exploration with attempted curative resection should be attempted on virtually all patients with islet cell tumors of the pancreas who do not have metastatic disease evident on preoperative studies. Because of the small size and variable location of many of these neoplasms, localization studies play an important role in ensuring appropriate and successful surgical therapy. A review of currently available preoperative and intraoperative aids for tumor localization is presented. A new technique of selective intraarterial injection of methylene blue is described along with a report of our preliminary results. Further evaluation and use of this technique and other newly developed technologies are warranted to lower the commonly reported 10% to 30% negative exploration rate for these sometimes elusive tumors.