Gassman's debut was in Milan, in 1942, with Alda Borelli in Niccodemi's "La Nemica" (theatre). He then moved to Rome and acted at the "Teatro Eliseo" joining Tino Carraro and Ernesto Calindri in a team that remained famous for some time; with them he acted in a range of plays from bourgeois comedy to sophisticated intellectual theatre. In 1946, he made his film debut in "Preludio d'amore", while only one year later he appeared in five films. In 1948 he played in "Riso amaro".