The thallium-technetium subtraction technique, proposed originally by Ferlin and co-workers, is now widely used to localize parathyroid adenoma. We report here the case of a hypercalcemic woman, referred to our ward with the biologically assessed diagnosis of primary hyperparathyroidism. Thallium-technetium subtraction scintigraphy not only successfully localized the parathyroid adenoma but also revealed the existence of an autonomous nodule of the thyroid, which was not suspected. It has previously been shown that this method can localize parathyroid adenoma in cases of cold thyroid nodule. This report shows that this is also true in the case of hot thyroid nodule. No observations of concomitant parathyroid adenoma and autonomous nodule of the thyroid have been reported (at least during the two past decades). Is this association casual or has it never been noticed? Further examinations can be performed with thallium when a hot thyroid nodule is found in a hypercalcemic patient.