Bierbrauer's key works are his hypnosis pictures from the early 1950s and his somnambulistic works created in the last five decades, as well as his sculptures out of different materials.
The focus of his work is the human being. In his the early work pure representations of people, such as portraits and nudes can be found. As he approached in the course of his activities as an artist, physician and psychotherapist, the hidden content of the human psyche determined his works.
Bierbrauer painted the hypnosis images after stories and pictures from his patients in trance. They were created after the end of World War II created until the early 1950s. The images based on Bierbrauers knowledge to find ways to help patients to developed their experiences through war and personal past traumas to free the hypnosis and the narration behind their images, in which he told these pictures were painted for the patients, in order to discuss connected with them. Like this, Bierbrauers were not only able to help his patients, but to make entirely new works of art through the assistance of the patient. In his understanding the artist can be a healer of the sick individual in the society. With these works he had been one of the pioneers of the conceptual art of the sixties in Europe.