The authors take in consideration the sensitivity of imaging methods in localization of adenomas and hyperplastic glands in primary and secondary hyperparathyroidism. Advantages and limits of Ultrasound, Computed Tomography, Magnetic Resonance Imaging and Dual Isotope Subtraction Scintigraphy are considered, specifying the correct technique of execution and the indications for each examination. The sensitivity of these imaging methods is fairly good, but inferior in comparison to surgical exploration of the neck; it has been seen that this value improves sensibly when a two-study combination is considered as a single test. After a wide review of the literature and considering their experience, the authors stress the opportunity of a routinary preoperative use of diagnostic imaging, both in primary intervention and in case of reintervention. According to the authors US and MRI are the best imaging modalities: US are of simple execution, non-invasive and have a high sensitivity in the localization of adenomas in the typical location; MRI is a multiplanar technique, has a high contrast resolution and a very good capability of exploring the neck and mediastinum, allowing the localization of ectopic adenomas.