OBJECTIVE: The objective was to evaluate the association of well-differentiated thyroid carcinoma and parathyroid pathology. METHODS: The medical records of 14 patients with concomitant pathologies were retrospectively reviewed. RESULTS: Parathyroidectomies (1.3%) and thyroidectomies (3.5%) performed for well-differentiated thyroid carcinoma resulted in the diagnosis of concomitant pathologies. Five patients had a primary hyperparathyroidism (PHPT) and nine were operated for thyroidectomy with intraoperative finding of an enlarged parathyroid gland. Patients (64%) were normocalcemic preoperatively. Thirteen had papillary carcinoma. Fifty percent of patients had multiple foci of papillary microcarcinoma. Twenty-nine percent of patients had parathyroid hyperplasia. All patients with preoperative hypercalcemia normalized their serum calcium. During follow-up, thyroglobuline, calcium serum values and cervical ultrasound showed no evidence of recurrence of the diseases. CONCLUSIONS: These observations stress the importance of pre and intraoperative evaluation to detect overt thyroid and parathyroid pathology before performing a parathyroidectomy for hyperparathyroidism or a thyroidectomy for a well-differentiated thyroid carcinoma.