The parathyroid glands are located posterior to the upper and lower poles of the thyroid and are derived from the third and fourth pharyngeal pouches. Usually there are only 2 superior glands, whereas only 40% of patients have their inferior glands located near the inferior thyroid poles. Ectopic locations include the carotid sheath, anterior mediastinum, retropharynx, or intrathyroidal locations. Single photon emission computed tomography/computed tomography (SPECT/CT) offers the advantage of combining function and anatomy for exact localization of ectopic parathyroid adenomas. In this pictorial review, we present 4 cases of hyperparathyroidism caused by ectopic parathyroid adenomas and review the literature on the additional value of their localization with SPECT/CT. Combined SPECT/CT scanners permit more reliable localization of ectopic adenomas. The additional information can aid in exact preoperative localization. In one study of 16 patients, SPECT/CT identified 39% more lesions compared with SPECT imaging alone. In other comparisons of planar, SPECT and SPECT/CT imaging modalities, SPECT/CT permitted the highest reader confidence in localization, especially for mediastinal adenomas. Larger studies are needed to establish the role and cost-effectiveness of SPECT/CT.