 Dorn made his debut under the name of Frits van Dongen in "Op Hoop van Zegen" (1934) directed by Alex Benno.He had lead roles in "De Big van het Regiment" (1935), "The Cross-Patch" (1935), "Op Stap" (1936), and "Rubber" (1936).He appeared on stage in "Camille", "Ghosts" and "Journey's End".