Thyroid carcinoma is the most prevalent endocrine tumor, and the papillary carcinoma (PC) is the most common histological type. In the follow-up, after thyroidectomy serum thyroglobulin (s-Tg) is used as a marker to evaluate recurrence of thyroid carcinoma. In most cases, this parameter allows an adequate diagnosis, but occasionally s-Tg may miss the detection of a recurrence. We report a 57 year-old female and a 36 year-old male subjected to a total thyroidectomy for a papillary thyroid carcinoma with intermediate and high-risk of recurrence. Both had a cervical recurrence without a concomitant increase in s-Tg levels. In both, Tg staining was positive in the tumor cells. These cases confirm that in these patients, the follow-up must be done with measurement of s-Tg and complementary diagnostic tests.