The offer of "integrative oncology" is one option for clinics to provide safe and evidence-based complementary medicine treatments to cancer patients. As known from merger theories, corporate culture and integration models have a strong influence on the success of such integration. To identify relevant corporate culture aspects that might influence the success in two highly visible integrative oncology clinics, we interviewed physicians, nurses, practitioners, and managers. All interviews (11 in a German breast cancer clinic and 9 in an integrative medicine cancer service in the USA) were audio-recorded, transcribed and analyzed with content analysis. According to the theoretical framework of mergers, each clinic selected a different integration type ("best of both worlds" and "linking"). Nonetheless, each developed a similar corporate culture that has a strong focus on research and safe and evidence-based treatments, and fosters a holistic and patient-centered approach. Structured communication within the team and with other departments had high relevance. Research was highlighted as a way to open doors and to facilitate a more general acceptance within the hospital. Conventional physicians felt unburdened by the provision of integrative medicine service but also saw problems in the time required for scheduled treatments, which often resulted in long waiting lists.