The frequency of the ectopic parathyroid glands has been reported to be 7-46% by anatomists or surgeons, while the proper frequency is still unknown. Recently the diagnostic methods of hyperparathyroidism have been developed, and many surgeons select total parathyroidectomy for renal hyperparathyroidism. Therefore the frequency of the ectopic glands has been supposed to be higher than that recognized previously. We investigated 97 patients with renal hyperparathyroidism, and detected 60 ectopic glands in 34 patients (35.1%). The ectopic glands existed in the mediastinum, intrathyroid, carotid sheath, post-pharynx, para-esophagus, and other regions. We describe the features of procedures for detecting ectopic glands. Using non-invasive examination, including ultrasonography, scintigraphy (T1 201-Tc 99 m), and MRI, will be a great assistance in the diagnostic procedures.