In over 80% of cases, primary hyperparathyroidism results from hypersecretion of PTH by a single parathyroid adenoma. Multi-glandular involvement, combining adenoma and/or hyperplasia in varying proportions, is also possible, although less frequent. When the diagnosis of hyperparathyroidism is certain and surgery is envisaged, imaging is useful for locating the hyperfunctioning gland or glands. First-line exploration is based on a parathyroid ultrasound and a nuclear medicine examination, which may be parathyroid scintigraphy, preferably double isotope I/^12399m Tc-sestamibi, with planar and tomoscintigraphic acquisitions, or a PET-CT scan with ¹⁸F-choline. In the event of negative results, it is advisable to perform a choline PET scan if the initial examination was scintigraphy. In difficult situations, additional investigations using 4D parathyroid CT or parathyroid MRI, fine-needle aspiration cytology and determination of PTH in the flushing fluid are possible after multidisciplinary discussion in an expert center.