Altstätten is a small historic rural town and a municipality in the district Rhine Valley, in the canton of St. Gall in Switzerland.

The town consists of the following tracts: Alter Zoll, Altstätten, Bächis, Baumert, Bieser, Büeberg, Bühl, Bühl (Gätziberg), Bühl bei Hinterforst, Burgfeld, Bürglen, Burst, Domishäuser, Fidern, Gätziberg, Gfell, Hoher Kasten, Hub, Kornberg, Krans, Kreuzstrasse, Lithen, Lienz (exclave), Lüchingen, Mariahilf (monastery), Oberbüchel, Plona, Riet, Rosenhaus, Ruppen, Strick, Unterlitten, Warmesberg, Weidest und Ziel.

In Altstätten has the start of the rack-and-pinion railway line of the Appenzeller Trams to Gais.

Supra-regional popularity was attained by Altstätten by its long and upscale Shrove-Tuesday tradition (carnival).

Each January and February performances are held by the Röllelibutzen-club, founded in 1919, as well as many of the town's and region's Youth Music Societies.

Of the rest of the land, 12.7% is settled (buildings or roads) and the remainder (2.9%) is non-productive (rivers or lakes).

The traditional farming city is located on the western side of the Rhine river between the Appenzell hill country.

Of the foreign population, (as of 2000[update]), 175 are from Germany, 228 are from Italy, 1108 are from ex-Yugoslavia, 143 are from Austria, 82 are from Turkey, and 316 are from another country.

[10] The age distribution, as of 2000[update], in Altstätten is; 1,296 children or 12.5% of the population are between 0 and 9 years old and 1,438 teenagers or 13.9% are between 10 and 19.

[10] The historical population is given in the following table:[5] From the 2000 census[update], 6,216 or 59.9% are Roman Catholic, while 2,050 or 19.7% belonged to the Swiss Reformed Church.