Background: To assess the personal beliefs of radiation oncologists regarding heart sparing techniques in breast cancer patients. Methods: Between August 2015 and September 2015, a survey was sent to radiation oncology departments in Germany, Austria and Switzerland. 82 radiation oncology departments answered the questionnaire: 16 university clinics and 66 other departments. Most (87.2%) of the participants had > 10years of radiation oncology experience. Results: 89.2% of the participants felt that there is enough evidence to support heart sparing for breast cancer patients. The most important dose parameter was considered the mean heart dose (69.1%). The personal "safe" dose to the heart was considered to be 5Gy (range: 0-40Gy). The main impediment in offering all breast cancer patients heart-sparing techniques seems to be the fact that these techniques are time/ resource consuming (46.5% of the participants). Conclusions: Most radiation oncologists believe that there is enough evidence to support heart sparing for breast cancer patients. But translating this belief into a wide practice will need better dosimetric and clinical data on what patients are expected to profit most, specific guidelines for which patients' heart sparing techniques should be performed, as well as recognition of the time/resource consumption of these techniques.