Unterstammheim is a former municipality in the district of Andelfingen in the canton of Zürich in Switzerland.

Of the rest of the land, 10.6% is settled (buildings or roads) and the remainder (0.4%) is non-productive (rivers, glaciers or mountains).

Most of the population (as of 2000[update]) speaks German (96.1%), with Albanian being second most common ( 1.8%) and Portuguese being third ( 0.6%).

In the 2007 election the most popular party was the SVP which received 35.7% of the vote.

[3] Stammheim railway station, situated in Unterstammheim, is served by Zurich S-Bahn line S29, which links Winterthur and Stein am Rhein.