Rheinau (German pronunciation: [ˈʁaɪnaʊ]) is a municipality in the district of Andelfingen in the Canton of Zürich in Switzerland.

It is located at a bend of the Rhine River which forms the Swiss-German border in this area.

A bridge links Rheinau to Altenburg, part of the municipality of Jestetten, Baden-Württemberg state.

Of the rest of the land, 11.3% is settled (buildings or roads) and the remainder (7.2%) is non-productive (rivers, glaciers or mountains).

Altenburg-Rheinau was one of only three Swiss operated stations located entirely within Germany, the other two being Jestetten and Lottstetten.

Notwithstanding protests from the German authorities,[5] the Swiss closed the station after 113 years of service, due to low passenger numbers.