OBJECTIVE Carcinoma of the parathyroid gland is a rare disease representing 0.5 to 4% of patients with primary hyperparathyroidism. We reviewed our experience with this disease, with special emphasis on the role of adjuvant postoperative radiotherapy. METHODS A retrospective review was conducted of all cases of parathyroid carcinoma referred to the Princess Margaret Hospital (PMH) from 1958-1996. Ten patients were identified. Their clinical features, management details, and treatment outcome are described. RESULTS There were 5 men and 5 women with a mean age of 53 years. Of these, 7 patients underwent en bloc resection; among them, 4 had neck dissection or lymph node sampling. The other 3 patients underwent only limited surgery to remove the tumor. Seven patients were referred for consideration of adjuvant radiation treatment. Six patients were given adjuvant radiation therapy for microscopic residual disease. All patients tolerated the radiation treatment well, with minimal side effects. The 7 patients have been followed regularly with no evidence of recurrence and normal serum calcium. The mean follow-up for the 6 patients who had adjuvant radiotherapy was 62.3 months (range 12 to 156 months). The remaining 3 patients had metastatic disease and were referred for palliative radiotherapy. CONCLUSIONS Our results in a small number of patients suggest local radiation therapy to the tumor bed may have eliminated the strong predilection for local recurrence of this disease, as reported by other investigators.