Mairengo is a former municipality in the district of Leventina in the canton of Ticino in Switzerland.

[2] During the Middle Ages the village belonged to the Degagna of Tarnolgio, which was part of the Vicinanza of Faido.

The parish of Mairengo also included Faido, Osco, Calpiogna and Campello.

The current building was restored in 2001, but still bears traces of the old romanesque church facade.

The local economy was based on livestock, which had virtually disappeared at the end of the 20th century, although the alpine pasture of Alp Formazzora in the Bedretto valley was still cultivated.

The village section of Polmengo is home to a large construction site for the new Gotthard Base Tunnel.

[2] Mairengo has an area, as of 1997[update], of 6.65 square kilometers (2.57 sq mi).

[3] The municipality is located in the Leventina district, on a terrace on the left side of the mid-Leventina valley.

It consists of the village of Mairengo and the hamlets of Tortengo, Raslina and Polmengo.

The blazon of the municipal coat of arms is Chequy Argent and Gules overall a bull's head caboshed Sable.

[6] The age distribution, as of 2009[update], in Mairengo is; 17 children or 3.0% of the population are between 0 and 9 years old and 31 teenagers or 5.4% are between 10 and 19.

[10] About 57.4% 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).

[7] The historical population is given in the following table:[2] The parish church of S. Siro is listed as a Swiss heritage site of national significance.

The walls also feature a mural from 1558 by Gerolamo Gorla da Milano and paintings from the 17th century.

[16] In the 2007[update] Gran Consiglio election, there were a total of 170 registered voters in Mairengo, of which 117 or 68.8% voted.

[7] There were 115 residents of the municipality who were employed in some capacity, of which females made up 33.0% of the workforce.

[7] From the 2000 census[update], 200 or 73.5% were Roman Catholic, while 13 or 4.8% belonged to the Swiss Reformed Church.

In the lower secondary school system, students either attend a two-year middle school followed by a two-year pre-apprenticeship or they attend a four-year program to prepare for higher education.

The professional program lasts three years and prepares a student for a job in engineering, nursing, computer science, business, tourism and similar fields.