The striking hospital doctors caused a stir in 2005. Their demand for higher pay and better working conditions was supported by the Marburger Bund, which was hardly known to the general public. Previously, ver.di, as a multi-sector union, represented all employees in hospitals. In the aftermath of the strikes, the doctors' association succeeded in establishing independent, physician-specific collective agreements. This changed the established constellation of actors in labor relations within the hospital sector. At the same time, the Marburger Bund transformed from a professional association focused on political issues into a trade union. Samuel Greef outlines the background of the doctors' strike and analyzes the transformation process of the Marburger Bund as well as the conditions for its success.