Ermensee is a municipality in the district of Hochdorf in the canton of Lucerne in Switzerland.

Of the rest of the land, 5.4% is settled (buildings or roads) and the remainder (0.4%) is non-productive (rivers, glaciers or mountains).

Of the agricultural land, 53.51% is used for farming or pastures, while 5.44% is used for orchards or vine crops.

Of the settled areas, 2.46% is covered with buildings, 0.53% is industrial, 0.35% is classed as special developments, 0.35% is parks or greenbelts and 1.75% is transportation infrastructure.

Most of the population (as of 2000[update]) speaks German (96.1%), with Albanian being second most common (1.7%) and Serbo-Croatian being third (0.7%).

The age distribution in Ermensee is; 212 people or 25.7% of the population is 0–19 years old.

In the 2000 census[update] the religious membership of Ermensee was; 633 (84.9%) were Roman Catholic, and 64 (8.6%) were Protestant, with an additional 8 (1.07%) that were of some other Christian faith.