The ability to image the parathyroid glands with scintigraphy dates back to 1964 when Potchen and Sodee visualized a parathyroid adenoma using Se-75 selenomethionine in a 31-year-old male suffering from painful bone disease. In the ensuing 45 years, imaging of the parathyroid glands evolved to include the administration of 99m-technetium sestamibi (“MIBI”) followed by a planar scintigraphic technique. Tomographic imaging of pathologic glands using single-photon emission-tomography (SPECT) gained favor in the early 2000s due to its positive effects on lesion detectability and interpreter confidence. Coupled with intraoperative gamma detectors, the localization of parathyroid gland disease has translated to improved surgical planning, efficiency, and outcomes. This chapter discusses the current literature regarding the use of planar and SPECT-CT-enabled evaluation of eutopic and ectopic parathyroid disease, primarily in patients with primary hyperparathyroidism.