Purpose : To understand the various clinical and radiological features of ectopic thyroid. Materials andMethods : This study involved nine ectopic thyroid cases (M:F=2:7; age range, 2-57 years) confirmed by RI thyroidscan between 1993 and 1997. We analyzed one neck ultrasonogram, five CT scans, three MR images, nine Tc-99mthyroid scans, and classified the ectopic thyroid by the basis of these findings. Hormonal abnormalities andsymptoms were evaluated on the basis of medical records. Results : The status of nine patients was found to beeuthyroid (n=6), hypothyroid (n=2) or hyperthyroid (n=1). Among the nine, the ectopic thyroid was lingual (n=6),sublingual (n=3) or thyroglossal (n=1); one patient had both the lingual and sublingual types. Ectopic thyroid wasseen as a well-defined round mass, homogeneously enhanced on CT scan, homogeneously hyperechogenic onultrasonogram and of intermediate signal intense on MRI. All cases showed ectopic radioactivity uptake on Tc-99mthyroid scan. In eight patients, ectopic thyroid was the only hormone-producing thyroid tissue; one had bothnormal thyroid and ectopic thyroid tissue in a thyroglossal duct cyst. Among the six cases of euthyroidism,ectopic thyroid patients with the lingual type complained of throat discomfort. Those with the sublingual typecomplained of palpable neck mass, and preoperative evaluation of thyroglossal duct cyst showed that this wasectopic thyroid. Conclusion : Understanding the various clinical and radiologic features of ectopic thyroid canhelp accurate diagnosis and prevent unnecessary surgery or other procedure.