Adelaide of Eilenburg (c. 1030 – 26 January 1071) was a German noblewoman. She was a daughter of Margrave Dedi I of the Saxon Eastern March and his first wife, Oda of Lusatia.

In 1060, she married Margrave Ernest of Austria during his reign and became Margravine of Austria. He was a member of the House of Babenberg; she was his first wife. Adelaide and Ernest had four children:

• Leopold II (d. 1095)
• Adalbert I, Count of Pernegg (d. 1100)
• a daughter, who married Count Herman I of Poigen
• Justitia, married Count Otto II of Dießen-Wolfratshausen