The authors describe the diagnostic use of I-123 MIBG scintigraphy in a 61-year-old man who was thought to have a recurrence 25 years after a left adrenalectomy for a pheochromocytoma. Preoperative I-123 MIBG scintigraphy was performed twice along with intraoperative gamma probe localization of the lesions. The preoperative MIBG scintigraphy revealed three pathologic processes in the upper left abdomen, whereas computed tomographic scanning identified only one site of involvement. All three metastatic lesions were removed successfully with the aid of a gamma probe. Preoperative I-123 MIBG scintigraphy, combined with intraoperative gamma probe identification of I-123 MIBG foci, is feasible and a valuable tool to detect malignant masses possibly overlooked by other imaging techniques.