Ataxia-telangiectasia (AT) is a rare multisystem disorder characterized by progressive cerebellar ataxia, frequent sinopulmonary infections, and telangiectasia of bulbar conjunctiva and/or skin (1). Frequency of various malignant neoplasms in patients with AT has been estimated to be more than 120 times greater than that of age-matched controls (2). More than 80% of the reported malignant neoplasms in patients with AT were of lymphoreticular origin (2).We present a case of an 18-year-old female with AT who developed papillary carcinoma of thyroid.