Adelaide of Leuven (died c. 1158) was the wife of Simon I, Duke of Lorraine (1076–1138), in what is now France. She was the daughter of Henry III of Leuven and his wife Gertrude of Flanders. After the death of her husband, Adelaide retired to Tart Abbey.
The children of Simon I and Adelaide included:
Matthias I, Duke of Lorraine
Robert, Lord of Floranges
Agatha of Lorraine, wife of Renaud III, Count of Burgundy
Hedwige, wife of Frederick III, count of Toul
Bertha, wife of Margrave Hermann III of Baden
Mathilde, wife of Gottfried I, Count of Sponheim
Baldwin
John
When her husband died in 1138, Adelaide went to the Cistercian house of Tart. Later on, in 1148, Adelaide founded the abbey of Etanche in the diocese of Toul. She was also in correspondence with Bernard of Clairvaux, according to several letters written between the two.