SUMMARY LARGE SUBSTERNAL GOITER WITH HYPERTHYROIDISM, TRACHEAL COMPRESSION, VENA CAVA SUPERIOR AND HORNER'S SYNDROMES Substernal goiter is an important cause of mediastinal masses. In this article, we presented a patient with hyperthyroidism, tracheal compression, vena cava superior syndrome and Horner's syndrome due to large substernal goiter and we reviewed substernal goiters. We believe that this is the first cage having all of these components in the literature. Key words: Substernal goiter, Vena cava superior syndrome, Horner's syndrome. ÖZET Substernal guatrlar, üst mediastinal kitlelerin önemli nedenle¬rinden biridir. Bu yazıda, dev substernal guatra bağlı hipertiroidizm, trakea basısı, vena kava superior sendromu ve Hor¬ner sendromu gelişen hasta sunuldu. Bilgilerimize göre vakamız, tarif edilen bulguları birarada içeren literatürdeki ilk vakadır.