Subsequent to these appearances, Brinkmann was, together with Alan Alda, chosen from more than one thousand actors who auditioned for the Ford Foundation's experimental theatre program at the Cleveland Playhouse in Ohio.
The young couple opened their theatre in 1963 in a rented 99-seat auditorium in a downtown palace with a production of Jerome Kilty's Dear Liar, starring Brinkmann and Anthony Steel, directed by Franz Schafranek.
She also played the Lady in Shaw's Man of Destiny, Doris in The Owl and the Pussycat, Miss Prism in Oscar Wilde's The Importance of Being Earnest, and Amanda in The Glass Menagerie, which subsequently toured throughout Israel.
In the following season, 1976, Tennessee Williams honoured Vienna's English Theatre with the world premiere of The Red Devil Battery Sign, in which Brinkmann starred as the Woman Downtown.
Thomas Quinn Curtiss wrote in the International Herald Tribune that Williams had been "magnificently served by Vienna's English Theatre's production (directed by Franz Schafranek).
In June 1981, at the invitation of Professor Otto Molden, she performed Alan Levy's adaptation of The World of Ruth Draper at the opening of the Dialogue Congress Western Europe - USA in Alpbach in the Tyrol, Austria.
In October 1993, Ruth Brinkmann returned to the stage for the 30th anniversary production of the theatre in which she portrayed the author Helene Hanff in James Roose-Evans' adaptation of 84 Charing Cross Road.