The association of diffuse hyperthyroid goiter and thyroid cancer is rare and interesting, considering that both diseases affect the same organ but have different pathogenesis and prognosis- We report two patients that consulted for diffuse hyperthyroid goiter and were subjected to a subtotal bilateral thyroidectomy due to antithyroid drug failure. Pathological study revealed the coexistence of diffuse gland hyperplasia and a papillary thyroid carcinoma of less than 7 mm phi. In both cases, the thyroid remanent was ablated with radioactive iodine during the postoperative period and thyroid substitution was started.