Žitný ostrov, also called Veľký Žitný ostrov (Great Rye Island) (German: Große Schüttinsel or Great Schütt Island, Hungarian: Csallóköz) to differentiate it from Malý Žitný ostrov (Small Rye Island) (German: Kleine Schüttinsel or Little Schütt Island, Hungarian: Szigetköz), is a river island in southwestern Slovakia, extending from Bratislava to Komárno. It lies between the Danube, its tributary Little Danube and Váh.The island is a major part of the Danubian Flat. It is the biggest river island in Europe with an area of 1,886 km², being 84 km long and 15 to 30 km wide.
The main towns on the island are Komárno, Dunajská Streda, and Šamorín. The island is an important reservoir of drinking water and an agricultural region.
Southern parts of Žitný ostrov by the Danube are protected by Dunajské luhy Protected Landscape Area.
Coordinates: 47°57′N 17°39′E / 47.950°N 17.650°E