[en] The radiobiology hypothesis is widely accepted by people that damage to the nuclear DNA is the main cause for the effects of radiation. However, some studies shown that the extranulear radiation effects are also very important, especially for mitochondria which contains the coding DNA and important proteins. Mitochondria plays a very important role in oxidative stress and cell death after irradiation. Some experiments present the effects of ionizing radiation on the mitochondria. Here, we discussed the ionizing radiation how to influence the mitochondria. And authors summary some available research data that specific protection of mitochondria could reduce damage to healthy cells exposed to ionizing radiation. (authors)