In recent years, radiological procedures in medical practice have been increased dramatically. The average radiation exposure from medical procedures and nuclear medicine was estimated to be 3.0 mSv year−1 in the United States, and 2.1 mSv year−1 in South Korea. Radiotherapy and radioisotope therapy are also increasing with the rising incidence of various cancers. Most of patients and physicians understand the concept of risk-benefit assessment and accept the benefit of such procedures that exceed the risk from radiation exposure. However, some patients and their caregivers have overconcern about the radiation exposure. On the other hand, a few do not pay any attention to the radiation protection. Thus, appropriate communication between the physicians, patients and their caregivers are required for optimal patient care and radiation protection. The communication should be based on scientifically appropriate risk assessment. Currently, dosimetry schemes for radiological procedures are well established, and there are considerable epidemiological data about the radiation effect on human health. A physician should be aware of the radiation dose and its effect, when performing a radiological procedure. Also, the purpose and need for radiological diagnosis or treatment should be discussed between the physician and the patient. Reliable quantitative assessment of risk and benefit is the beginning of the communication. In communication with those who have overconcern about radiation exposure, some principles need to be noted to improve emotional perception of the risk, such as high understanding, self-decision, and self-control. For better understanding of the radiation hazard, its amount needs to be understood in comparison with those of other well-known risk factors, such as traffic accident, surgical anaesthesia, and bike riding. Exaggerated or even false information from media or film should be avoided. It is also necessary to give sufficient information on the disease status and other available diagnostic and therapeutic options, except radiological procedures. When the decision for a certain radiological procedure is made by patient, the emotional perception would be improved. Additionally, it is also good to provide guidance for self-controlling radiation dose, if available. In case of radioisotope treatment, there are several preparation methods and guidance for patients to reduce radiation exposure of themselves and their caregiver. In summary, physicians’ communication with patients on radiation risk should be based on scientific data, sufficient information, and sharing of decision and control with patients.