Among 334 neck explorations for primary hyperparathyroidism (pHPT) between 1979 and 1993 120 (33,9 %)thyroid operations were performed simultaneously. Histologic examination revealed 40 thyroid adenomas, 43 nodular goiters, 8 thyroiditis and 9 differentiated carcinomas. In 20 cases the indication was doubtful retrospectively, as evaluated by postoperative histology. Of the 9 carcinomas there were 4 small papillary, 3 papillary pT(2) No Mo and 2 follicular pT(2) No Mo.Perioperative morbidity of the simultaneous operations was not significantly increased compared to the parathyroid exploration alone. We conclude, that pre- and intraoperative thyroid examination should be performed in pHPT and decision for a simultaneous operation should be made generously.