Background: Although ionizing radiation is very important in diagnostic and treatment of many diseases, the hazards of this radiation are considerable and irrefutable. One of the main stages in radiation protection is knowledge about radiation dose in radiological investigation. The aim of this study was to determine the physicians' knowledge in radiological examinations. Materials and Methods: The data collected by questionnaire were designed and the most commonly requested radiological investigations were listed. The questionnaire was distributed among 106 consultant physicians. The survey was conducted on the awareness about the radiation dose and risks among health professionals in Iran. Results: The results indicated that the majority of physicians did not know about ionizing radiation and evaluation of absorbed dose in patients. Many of these physicians were not aware of radiations risks and the most important aspects of radiation protection; although, they have passed some courses in radiobiology and medical physics. Conclusion: Since radiological examinations play an indispensable role in medicine, knowledge about radiation doses and hazards is very important. Generally, this study showed that knowledge of radiation doses is inadequate among physicians.