The objective was to evaluate the association of well-differentiated thyroid carcinoma and parathyroid pathology.The medical records of 14 patients with concomitant pathologies were retrospectively reviewed.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.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.