Aristau is a municipality in the district of Muri in the canton of Aargau in Switzerland.

The first traces of human settlement around Aristau are scattered La Tène culture artifacts.

The modern municipality of Aristau is made up of three separate sections or villages.

During the Late Middle Ages it was the possession of the lords of Baar and Muri Abbey.

In 1351 Catherine of Baar sold the rights and property in Aristau to Hartmann Heidegg.

The ruins of Werd Castle (of which no records exist) was possibly the home of the Lords of Aristau.

With the completion of the Wendelin Church in 1943, Aristau became the center of the newly independent Reusstalpfarrei (Reuss valley parish).

[5] The municipality is located in the Muri district, on the eastern slope of the Wagenrain hills above the Reuss river valley.

The blazon of the municipal coat of arms is Gules a Tower Argent embattled masoned issuant from a Mount Vert between two Mullets of the second.

[9] The age distribution, as of 2008[update], in Aristau is; 122 children or 9.4% of the population are between 0 and 9 years old and 193 teenagers or 14.9% are between 10 and 19.

[11] About 61% of the total households were owner occupied, or in other words did not pay rent (though they may have a mortgage or a rent-to-own agreement).

[9] From the 2000 census[update], 678 or 56.6% were Roman Catholic, while 309 or 25.8% belonged to the Swiss Reformed Church.