OBJECTIVE Adequate management of parathyroid carcinoma apparently relates to the surgeons ability to identify it at the first operation. The objective of this paper was to evaluate the role of clinical suspicion in the management of parathyroid carcinoma. METHODS Retrospective analysis of parathyroid carcinoma patients treated in Department of Head and Neck Surgery, Faculdade de Medicina da Universidade de São Paulo. METHODS Cross-sectional study of 143 patients who underwent surgery from 1995 to 2000, due to hyperparathyroidism. These cases were reviewed to ascertain whether preoperative and intraoperative suspicion of parathyroid carcinoma were helpful during the operation, and which factors demonstrated the suspicion of cancer best. RESULTS Among 66 patients with primary hyperparathyroidism there were four cases of parathyroid carcinoma (6.1%), and one case was found in secondary hyperparathyroidism (1.3%). Palpable nodules were found in five patients with primary hyperparathyroidism, four of them with parathyroid carcinoma. Preoperative levels of calcium in primary hyperparathyroidism with cancer patients varied from 12.0 mg/dl to 18.2 mg/dl. Two patients had gross macroscopic spread of the tumor to adjacent structures. Except for one patient, with extensive disease, tumors were resected en bloc. In secondary hyperparathyroidism, parathyroid carcinoma was found in a fifth mediastinal gland. One atypical adenoma was observed. CONCLUSIONS High levels of calcium, palpable tumors and adherence to close structures are more common in parathyroid carcinoma. These clinical signs may be helpful for decision-making during parathyroid surgery.