Abstract: Objective : To examine the clinical presentation, diagnosis and prognosis of secondary neoplasm of the thyroid. Method : Nine patients with secondary cancer of the thyroid, with a median age of 51, were analyzed retrospectively. All the patients underwent thyroid ultrasonography. Fine-needle aspiration cytology of the thyroid (FNAC) was performed in five of the patients. Tissue diagnosis was obtained by thyroidectomy in four patients. The most frequent original tumor was the esophageal carcinoma (3/9), lung cancer(3/9) and renal clear cell carcinoma(RCC), melanoma, and larynx carcinoma for one case each. The time between diagnosis of the primary tumor and detection of thyroid invasion in the patients ranged from 1 to 48 months (mean, 8). Results : All patients died within ten months, after diagnosis, except for one with RCC who lived for seven years and a half. Conclusion : Metastasis in the thyroid gland was uncommon and may be a diagnostic problem. Its presence often indicated a poor prognosis with the exception of RCC. Ultrasonography, FNAC and immunohistochemistry were valuable for diagnosis.