['Today, minimizing the operating time makes preoperative hyperparathyroid lesion localization more valuable and it is routinely performed through ultrasound (US) and/or nuclear imaging (NI). We evaluated the accuracy of US and NI, used separately or concurrently, in the preoperative identification and localization of hyperparathyroid lesions.', 'Retrospectively, patients receiving a parathyroidectomy for primary hyperparathyroidism from January 1985 through August 2000 were reviewed. The demographics, operative characteristics, serum laboratories, pathology, and radiology results were evaluated.', 'A total of 226 operations were performed including 160 adenomas, 64 hyperplasia, and 2 carcinomas. For US the sensitivity was 67%, specificity 33%, and positive predictive value (PPV) 82%. For NI these values were 67%, 55%, and 86%, respectively. When either US or NI were positive, the results were 82%, 29%, and 85%, respectively. When both were positive, the results were 53%, 71%, and 90%, respectively. When both were positive, and had side concordance, the results were 53%, 100%, and 100%, respectively.'] Do preoperative ultrasound and nuclear medicine studies improve the accuracy in localization of adenoma in hyperparathyroidism?