One of the four daughters of Prince Kazimierz I and Eufemia of Mazovia. She was sent to the Cistercian convent in Trzebnica. About 1360 she started a relationship with the Margrave of Moravia, Jan Henryk. Pope Urban V intervened in the matter and, in a letter dated 20 January 1364, ordered the Bishop of Wrocław, Przecław of Pogorzela, to persuade the Margrave and Elżbieta to end the relationship and make her return to the convent. This suggests that Elżbieta had already taken her final vows. The motives behind the Margrave's actions are not clear, and he probably never intended to marry Princess Elżbieta, since almost at the same time he married Margaret, the daughter of the Prince of Austria, Albrecht II (it being his third marriage). 

(K. Jasiński, Rodowód, vol. 3, pp. 147-148, I. Panic, Tragiczna miłość, pp. 40-41)