Preoperative sestamibi (MIBI) and ultrasonography (US) are used to localize parathyroid tumors in patients with primary hyperparathyroidism (pHPT). The intraoperative quick PTH assay (qPTH) has been recommended to determine whether all hyperfunctioning parathyroid tissue has been removed. We questioned whether qPTH improves the results of parathyroidectomy in patients with pHPT. We analyzed 115 unselected patients with pHPT without a family history or multiple endocrine neoplasia but who had undergone parathyroidectomy. All 115 patients had successful operations without complications. Of these patients, 88 (77%) had solitary adenomas, 13 had double adenomas, 1 had triple adenomas, 12 had hyperplasia, and 1 had carcinoma. Overall, MIBI was correct in 72% (76/106), US in 49% (49/99), and qPTH in 80% (92/115). For preoperative studies showing a single tumor, MIBI was correct in 83% (73/88), US was correct in 71% (45/63), and combined MIBI and US were correct in 95% (37/39). Adding qPTH in this subgroup did not improve the successful focused approach: 70% for MIBI, 65% for US, and 87% for combined MIBI and US. However, adding qPTH improved the overall success of parathyroidectomy (MIBI 92%, US 86%, combined MIBI and US 97%), but at the cost of unnecessary further exploration (MIBI 13%, US 6%, combined MIBI and US 8%). We conclude that when the same solitary tumor is identified by both MIBI and US, a focused exploration can be done with a 95% success rate. Adding qPTH to MIBI or US can improve the success rate but at a significant cost. General exploration of all parathyroid glands, however, has the highest success rate (100%).