Purpose: The thyroglossal duct runs from the base of the tongue to the thyroid. Rarely the thyroid completely fails to migrate and results in ectopic thyroid tissue, which can be demonstrated scintigraphically. A 31-year old female patient was referred for thyroid scintigraphy due to protruding mass at the base of the tongue. She was mildly hypothyroid. Tc-99m pertechnetate thyroid scan was performed to rule out ectopic thyroid gland. There showed a focal area of intense tracer uptake in sublingual area, suggesting the sublingual thyroid. In addition there noted diffusely increased tracer uptake in both breasts. The patient delivered a baby 6 months prior to the scan and was on breast-feeding. Free Tc-99m pertechnetate physiologically secrets into the salivary glands, the stomach, the gastrointestinal tract, the genitourinary tract and the mammary glands and sodium-iodide symporter plays a role in the accumulation of free Tc-99m pertechnetate. We report simultaneous visualization of lactating breasts and ectopic thyroid gland in the base of the tongue.(Korean J Nucl Med 39(6):489-490, 2005)