Serum thyroglobulin (Tg) is not a reliable tumor marker for monitoring disease status after treatment in patients with papillary thyroid carcinoma (PTC) with positive anti-thyroglobulin antibody (TgAb). The aim of this study was to evaluate the clinical role of circulating epithelial cells (CECs) in PTC patients with positive serum TgAb and undetectable serum Tg. A pilot study was performed to evaluate CECs in 25 PTC patients with positive serum TgAb and undetectable serum Tg. CECs were isolated and enriched from peripheral blood with a negative selection system PowerMag. Immunofluorescence staining with anti-epithelial cell adhesion molecule (anti-EpCAM) and anti-thyroid stimulating hormone receptor (anti-TSHR) antibodies were used to define EpCAM+-CECs and TSHR+-CECs. After CECs testing, 25 patients were classified into two groups: recurrence group (n=7) and remission group (n=18) based on biopsy or imaging studies. The diagnostic accuracy and cutoff points of EpCAM+-CECs and TSHR+-CECs were evaluated using receiver operating characteristic (ROC) curves. The optimal cut-off values of CECs were determined by the Youden index (sensitivity+specificity−1). The median numbers of EpCAM+-CECs (72.5 vs. 10.75) and TSHR+-CECs (54 vs. 5.25) were significantly increased in recurrence group compared to remission group. The area under the curve (AUC) showed good performance of EpCAM+-CECs (0.937) and TSHR+-CECs (0.825) to discriminate between recurrence and remission. The cut-off value for EpCAM+-CECs and TSHR+-CECs were set at 48cells/ml and 10cells/ml, respectively and showed a sensitivity (EpCAM+-CECs: 85.7%; TSHR+-CECs: 85.7%) and a specificity (EpCAM+-CECs: 100%; TSHR+-CECs: 77.8%) in predicting the recurrence. Our study suggests CECs testing could be a potential biomarker to identify recurrence in PTC patients with positive serum TgAb and undetectable serum Tg. •Serum levels of EpCAM+-CECs and TSHR+-CECs were significantly higher in PTC patients with positive serum TgAb and undetectable serum Tg who will have recurrence.•The count of EpCAM+-CECs may be an independent biomarker to predict recurrence in this special population.•CECs testing could be a potential biomarker to identify recurrence in PTC patients with positive serum TgAb and undetectable serum Tg.