Ectopic thyroid is defined as thyroid tissue not located anterolaterally between the second and the fourth tracheal cartilage. This anomalous localization results from abnormal embryologic development and/or migration of the gland. The purpose of this study is to demonstrate the role of imaging in the preoperative evaluation of ectopic thyroid.A 13-year-old girl with no other significant medical history, consulted for dysphonia, fullness in the throat and breathing difficulties. Examination of the oral cavity and oropharynx showed a large mass attached to the base of the tongue, the mass was evaluated by ultrasanography, computed tomography, magnetic resonance imaging and scintigraphy.Ultrasound sonography showed a well-defined hypoechogenic mass in the posterior end of the tongue. Scintigraphy showed hyperfixation at the base of the tongue with no fixation in the normal thyroid site. Computed tomography scan revealed a spontaneously hyperdense spherical basilingual mass with a high enhancement after contrast injection. In MRI, the mass was isointense with the muscle in T1-weighted images and hyperintense in T2 weighted images.Ectopic thyroid must be evoked in the presence of any basilangual mass. Scintigraphy and ultrasanography are gold standard in demonstration the ectopic thyroid tissue. But computed tomography and MRI playing an increasingly important role in the diagnosis, in determination of the malignant transformation and planning the surgical approach.