Background. Thyroidectomy is one of the most frequently performed surgical procedures worldwide. Despite technical advances and high experience of thyroidectomy of specialized centers, it is still burdened by a significant rate of postoperative complications. Among them, the skin sinus formation is an extremely rare postthyroidectomy complication. Here, we first report the incidence of the skin sinus formation after thyroidectomy to identify the causes for skin sinus formation after thyroidectomy and to discuss its prevention and treatment options. Methods. A retrospective analysis was carried out of patients who underwent excision operation of fistula for postthyroidectomy skin sinus formation. Data were retrieved from medical records department of the Affiliated Hospital of Inner Mongolia Medical University. Results. Of the 5,686 patients who underwent thyroid surgery, only 5 patients (0.088%) had developed skin sinus formation. All 5 patients successfully underwent complete excision of fistula. Conclusion. Infection, foreign body, thyroid surgery procedure, combined disease, and iatrogenic factors may be related with skin sinus formation after thyroidectomy. To reduce the recurrence of postoperative infections and sinus formation, intra- and postoperative compliance with aseptic processing, intraoperative use absorbable surgical suture/ligature, repeated irrigation and drainage, and postoperative administration of anti-inflammatory treatment are to be followed.