A 33-year-old man was admitted with a swelling in the right lobe of the thyroid gland of 1 years duration. Laboratory investigations and thyroid function tests were normal. Thyroid scanning showed a cold nodule in the lower pole of the right thyroid lobe. Thyroid ultrasonography showed multiple cystic nodules in the thyroid gland. To make a differential diagnosis of the thyroid nodule, fine-needle aspiration biopsy (FNAB) was performed and hydatic cyst of the thyroid gland was diagnosed. Subtotal thyroidectomy was carried out and histopathologic examination confirmed the diagnosis. During aspiration biopsy, the patient did not present a clinical picture of anaphylactic reaction. To our knowledge, this is the first case of thyroid hydatic cyst diagnosed by FNAB reported in the literature.