After her hometown became Polish after World War I, her parents moved to Stettin in 1920, where Zadek spent her youth; however as a Jew she was forced to leave Germany in 1934 and settled in then Palestine, where she worked as a nurse in Jerusalem, while studying voice with Rose Pauly. In 1945, she returned to Europe and studied in Zürich with Ria Ginster.
She made her operatic debut in 1947, at the Vienna State Opera, as Aida to great acclaim, she remained with this theatre for twenty years. The following year she first appeared at the Salzburg Festival, where she sang as Donna Anna, Vittelia, Ariadne. Her repertory also included; Elsa, Eva, Iphigénie, Tosca, etc. She took part in the creation of Carl Orff's Antigonae in 1949, and sang Magda Sorel in the local premiere in Vienna of Menotti's The Consul in 1950. She also appeared at the Munich State Opera and the Berlin State Opera.
She made guest appearances at the Royal Opera House in London, the Glyndebourne Festival and the Holland Festival, at the Paris Opéra, La Monnaie in Brussels, La Scala in Milan, the Maggio Musicale Fiorentino, the Bolshoi Theatre in Moscow, etc.
Beginning in 1967, she taught at the Vienna Music Academy, and gave masterclasses. She retired from the stage in 1971.
Decorations and awards
- Honorary member of the Vienna State Opera
- 1965 Austrian Cross of Honour for Science and Art
- Honorary Medal of Vienna in gold
- 2007 Honorary doctorate from the University of Music Karlsruhe (on her 90th birthday)
- Grand Decoration of Honour for Services to the Republic of Austria