The effectiveness of disinfecting archive documents by using ionizing radiation was investigated. Test samples were used to test the changes of the physico-chemical properties of paper under different radiation doses. It was found that a dose of 800 krad is sufficient to eradicate mildew spores occurring in archive depositories. This dose is responsible for a certain deterioration of the physico-chemical properties of the paper which, however, is not particularly conspicuous. After irradiation, certain reactions may be triggered in the paper, the effects of which may be manifest only after a longer interval following treatment. Evidence of this is the deterioration of the properties of treated paper which occurred in the course of accelerated aging.