Background: This study is conducted with the aim of determining the knowledge, attitude and behaviors of the personnel on radiation safety, who are exposed to radiation and working in a university hospital in Istanbul.  Materials and Methods: In this research, which is descriptive, a questionnaire that consists of 20 questions conducted to 101 healthcare personnel who are working with radiation source in operating room, endoscopy, radiology units. The obtained data is analyzed with Statistical Package for the Social Sciences (SPSS) 22.0 program and chi-square test is applied. Results: 58.4% of the participants are women and 41.6% of them are men. 32.7% of the participants stated that they got fluoroscopy education and 50.5% of them stated that they got dosimeter education. 64.4% of the participants stated that they use in fluoroscopic environment at least two times a day and 78.2% of them stated that they did not use legal ray permission. 2% of the participants stated that they do not know about the protective equipment that should be used during fluoroscopy. 74.3% of the participants stated that they do not feel qualified enough about radiation measuring and dosage units. Conclusion: Findings indicate that the healthcare personnel, who participated in this research and working with ionizing radiation sources, do not have the adequate knowledge about radiation safety. For this reason, the most important subject is that the managements of the institutions which are practicing radiation should take precautions with providing either personnel or necessary substructure in terms of equipment and necessary trainings.