Background: Complementary and alternative medicine (CAM) is used by many cancer patients in Germany. Yet, no data exist on CAM at certified cancer centers. Methods: We performed a survey at 44 certified oncology centers, 11 comprehensive cancer centers, and 746 certified organ cancer centers using a standardized questionnaire asking for meaning attributed to CAM, counseling on CAM, and CAM methods used. Results:50 oncology and comprehensive cancer centers (90.9%) and 186 organ cancer centers (25.5%) returned the questionnaire. 95% of the oncology and 83% of the organ cancer centers state that complementary medicine (CM) has a high impact on mental health. 56% of the oncology and 64% of the organ cancer centers make the same statement with regard to alternative medicine (AM). At 62% of the oncology and 54% of the organ cancer centers, counseling on CAM is offered. 9% of the oncology and 20% of the organ cancer centers state that CM is associated with risks. Conclusion: In certified cancer centers there is a high interest in CAM, and a substantial part of the centers offer counseling and treatment. The awareness of risks is relatively low. Education on CAM in oncology is mandatory in order to improve the safety of CAM use in cancer patients.