Ägerisee or Lake Aegeri is a glacial lake in the Canton of Zug, Switzerland. The two municipalities along its shore are Oberägeri and Unterägeri. The main tributary is the Hüribach; the Lorze river drains the Ägerisee. Since 1992 the lake has been used as a water reservoir.

The Battle of Morgarten took place in 1315 on the shores of the Ägerisee.

• List of lakes of Switzerland

Media related to Lake Ägeri at Wikimedia Commons

• Ägerisee in German, French and Italian in the online Historical Dictionary of Switzerland.
• Waterlevels at Unterägeri from the Swiss Federal Office for the Environment