In 56 postoperative patients with primary hyperparathyroidism we analysed retrospectively whether a single-sided or minimal invasive operative procedure could have been utilized. Additionally the sensitivity of (99m)TC-Sestamibiscintiscanning and ultrasound of the neck region was assessed. Single gland disease was found in 49 patients, 6 patients had primary multiglandular disease and one patient revealed a double adenoma. The overall sensitivity of (99m)TC-Sestamibiscintiscanning and ultrasound was found to be 78 % and 53 % respectively. In 46 patients the operation would have been started minimal invasive, in 7 of these patients a conversion to bilateral exploration would have been necessary because of four gland hyperplasia, double adenoma or misleading preoperative localisation. In 39 patients a successful minimal invasive procedure would have been possible. A primary bilateral exploration would have been necessary in 10 patients because of either coexisting goiter or questionable localisation of the pathological altered gland. Since sensitivity of localisation diagnostics is low with regard to multiglandular disease, parathyroid hormone should be monitored intraoperatively whenever minimal invasive operative procedures are performed.