In 1946, Nilsson made her debut at the Royal Opera in Stockholm with only three days' notice, replacing the ailing Agathe in Carl Maria von Weber's Der Freischütz. Conductor Leo Blech wasn't very kind to her and, as she wrote in her autobiography, she even contemplated suicide after the performance. In 1947 she claimed national attention as Verdi's Lady Macbeth under Fritz Busch. A wealth of parts followed, from Strauss and Verdi to Wagner, Puccini, and Tchaikovsky. In Stockholm she built up a steady repertoire of roles in the lyric-dramatic field, including Donna Anna, Aida, Lisa, Tosca, Venus, Sieglinde, Senta and the Marschallin, one of her favourite roles (though she later lamented that she was never asked to sing it outside of Stockholm), all sung in Swedish. In 1949 she sang Ariadne auf Naxos with Hjördis Schymberg and Elisabeth Söderström among others.