The Syrmia County (Hungarian: Szerém vármegye, Croatian: Srijemska županija, Serbian: Сремска жупанија) was an administrative unit (county) of the medieval Kingdom of Hungary in the Middle Ages. It was established in the 13th century, and included most of what is today Serbian Syrmia. It was subordinated to the Banate of Macsó. It was conquered by the Ottomans in 1526.