After attending the French School until she was 16, she studied song and dance under the operatic tenor Vilhelm Herold.
When she was 20, she entered the Opera Academy at the Royal Theatre where she made her début in 1934 as Micaëla in Carmen, becoming an immediate success.
[1] Her most effective roles were those in the Mozart operas, especially Fiordiligi and Despina in Cosi fan tutte, Papagena in The Magic Flute, Zerlina in Don Giovanni and Susanna in The Marriage of Figaro.
Many recordings were made in connection with the film Jeg har elsket og levet tracing the life of Christoph Ernst Friedrich Weyse.
[1] In 1949, Oldrup married the Swedish baritone opera singer Sigurd Carl Björling and moved to Sweden.