Best known to record collectors for her performances with the fledgling Glyndebourne Festival from 1934 to 1938, Luise Helletsgruber was a tall, slender lyric soprano whose principal activities otherwise centered about the Wiener Staatsoper. Her association with the latter institution concluded during WWII, but in her two decades of stage work, she achieved a reputation for reliable artistry, albeit a kind falling short of highest standards. After studies in her native city, Helletsgruber made her debut at the Staatsoper in 1922, singing the brief part of the shepherd in Tannhäuser. Her pleasing stage personality and attractive voice soon led her to such leading lyric roles as Eva, Cherubino, Dorabella, Micaëla, and Marguerite, with occasional ventures into slightly heavier roles such as Elsa in Lohengrin and Puccini's Liù. In 1934, she was engaged by John Christie for the first season of the Mozart festival conceived largely for an opportunity for Christie's wife, soprano Audrey Mildmay. Thus, the Austrian soprano joined international casts for performances of Così fan tutte (Dorabella) and Le nozze di Figaro (Cherubino) for the first season of what would become one of the world's most celebrated summer festivals. Under the conducting of Fritz Busch and the stage direction of Carl Ebert, Helletsgruber's instincts as a Mozartean were honed and she achieved a worthy reputation for her work in that repertory. For 1935, she repeated her Cherubino and Dorabella and added the First Lady in Die Zauberflöte. In 1936, Helletsgruber added Donna Elvira to her portrait gallery while repeating Dorabella and the First Lady. In her final year at Glyndebourne, Helletsgruber sang five more Dorabellas and shared Donna Elvira with another Viennese soprano, Hilde Konetzni. From 1928 to 1937, Helletsgruber also performed at Salzburg. Upon HMV's recording of Le nozze di Figaro, Don Giovanni, and Così fan tutte, Helletsgruber's work became a part of an important segment of music history; these recordings have seldom been out of the catalog since their issuance in the 1930s. In addition to fleeting moments recorded live on-stage in Vienna and a few studio arias, Helletsgruber is remembered for her singing of the soprano part in the fabled Felix Weingartner recording of Beethoven's Symphony No. 9, assembled from two separate series of sessions in 1935 and 1938.