Unterentfelden is a municipality in the district of Aarau of the Canton of Aargau in Switzerland.

Of the rest of the land, 37% is settled (buildings or roads) and the remainder (0.3%) is non-productive (rivers or lakes).

[3] The blazon of the municipal coat of arms is of a "Duck Marron statant on Coupeaux Vert and in chief three Mullets Gules in fess".

[3] As of 2008[update], the age distribution in Unterentfelden was as follows: 369 children or 9.8% of the population were between 0 and 9 years old and 389 teenagers or 10.3% were between 10 and 19.

[9] In the 2007 federal election the most popular party was the SVP, which received 36.4% of the vote.

[10] From the 2000 census[update], 935 or 29.3% are Roman Catholic, while 1,649 or 51.6% belonged to the Swiss Reformed Church.