Radiophobia is an obsessive fear of ionizing radiation, in particular, fear of X-rays. While in some cases radiation may be harmful (i.e. radiation-induced cancer, and acute radiation syndrome), the effects of poor information, understanding, or a traumatic experience may cause unnecessary or even irrational fear. The term is also used in a non-medical sense to describe the opposition to the use of nuclear technology (i.e. nuclear power) arising from concerns disproportionately greater than actual risks would merit.

Radiation, most commonly in the form of X-rays, is used frequently in society in order to produce positive outcomes. The primary use of radiation in healthcare is in the use of radiography for radiographic examination or procedure, and in the use of radiotherapy in the treatment of cancerous conditions. Radiophobia can be a fear which patients experience before and after either of these procedures, it is therefore the responsibility of the healthcare professional at the time, often a Radiographer or Radiation Therapist, to reassure the patients about the stochastic and deterministic effects of radiation on human physiology. Advising patients and other irradiated persons of the various radiation protection measures that are enforced, including the use of lead-rubber aprons, dosimetry and Automatic Exposure Control (AEC) is a common method of informing and reassuring radiophobia sufferers.

Similarly, in industrial radiography there is the possibility of persons to experience radiophobia when radiophobia sufferers are near industrial radiographic equipment.