The development of localization studies and quick parathyroid hormone assay (QPTH) has allowed the development of focused surgery in sporadic primary hyperparathyroidism. The aim of this investigation was to determine whether localization studies select a specific population of patients. From 1999 to 2001, 213 patients underwent surgery for sporadic primary hyperparathyroidism. All were investigated with sestamibi scanning and ultrasonography. When at least 1 study showed a positive result (n=175), the patient underwent a video-assisted approach with QPTH. When results were negative (n=38), the patient underwent cervicotomy and exploratory procedures of all 4 parathyroid glands. All patients are cured (mean follow-up, 17.8+/-10.3 months [SD]). Patients with negative preoperative study results had a high risk of multiglandular disease (12/38 patients; 31,6%), compared with patients with 1 positive study result (3/83 patients; 3.6%; P<.0001) and those with 2 concordant positive study results (0/92 patients; P<.0001). When preoperative localization study results are negative, the patient has a high risk of multiglandular disease, and a conventional cervicotomy with identification of the 4 glands is recommended strongly. When only 1 localization study is positive, the risk of multiglandular disease justifies the use of QPTH during a focused approach. When positive localization study results are concordant, the use of QPTH is questionable during a focused approach.