Parathyroid scintigraphy has been recommended in hyperparathyroidism for preoperative localization of parathyroid adenoma to avoid long and invasive neck exploration. Dual isotope scintigraphy (Tc-99m sestamibi/Tc-99m pertechnetate or I-123 iodine) can differentiate accurately a parathyroid from a thyroid adenoma, only the latter takes up both tracers. We report an unusual case where both Tc-99m sestamibi and I-123 iodine accumulated in a pathologically proven parathyroid adenoma.