6 patients were studied by <sup>201</sup>T1 scintigraphy; 1 of them suffered from a benign, and another from a malignant adrenal pheochromocytoma. 1 patient had a hormonal inactive adrenal tumor, 3 others multiple organ metastases of malignant pheochromocytomas. At the same time, 3 of the patients were studied by <sup>131</sup>I-metaiodobenzylguanidine (<sup>131</sup>I-MIBG) scintigraphy. Using different techniques like kinetic studies, whole-body scan or a <sup>201</sup>T1-<sup>99m</sup>-Tc difference scan, benign and malignant pheochromocytoma tissues could be localized by <sup>201</sup>T1 scintigraphy. Benign and malignant pheochromocytomas showed different kinetics of <sup>201</sup>T1. In 2 patients with multiple organ metastases of malignant pheochromocytomas, the metastases were partly imaged by <sup>131</sup>I-MIBG, the others by <sup>201</sup>T1.