This study analyses the diagnostic value of preoperative diagnostic imaging examinations in the identification and location of pathological parathyroid glands. We examined 77 patients with primary hyperparathyroidism using ultrasonography of the neck and Tc99m-MIBI scintigraphy for preoperative assessment purposes. All patients underwent surgical treatment. We compared the diagnostic imaging results with those furnished by histological examinations. TC99m-MIBI scintigraphy revealed the presence of a pathological parathyroid gland in 74/77 cases (96.1%) compared with 75/77 cases (97.4%) diagnosed by ultrasonography. The two examinations combined detected pathological glands in 100% of cases. The location of the pathological gland was correct in 57 cases (74.0%) at scintigraphy and in 56 cases (72.7%) at ultrasonography. In one case (1.3%) persistent hyperparathyroidism was demonstrated. There were no cases of relapse. In this study preoperative evaluation by ultrasonography and scintigraphy displayed great sensitivity in identifying and locating pathological parathyroid glands. Surgical neck exploration is still the gold standard in the correct location of pathological parathyroid glands measuring less than 5 mm.