Contamination of exhibition and storage rooms by insects and microorganisms and the resulting damage to objects of cultural value constitute a great problem in the conservation of cultural heritage. Until recently, one of the most widely used and apparently effective methods in the Netherlands to fight fungi and insects was fumigation with ethylene oxide. After an accident involving fumigation during which a collection of textiles was lost, and after research proved that ethylene oxide possesses carcinogenic properties, doubts arose regarding the use of ethylene oxide. Research also showed that materials containing proteins and fat retain gas residuals after treatment. An alternative to treatment with ethylene oxide may be gamma irradiation. The use of highly energetic, ionizing radiation (gamma, roentgen, beta) for decontaminating objects of cultural value has certain advantages. Radiation can be applied in a clean, quick, and simple manner. But the negative effects upon materials constitute a big problem. Insofar as is known, the dose that is necessary to kill microorganisms causes damage to materials containing cellulose, such as paper and textiles. To arrive at a final judgment about the long-term effects of gamma irradiation on paper, five different types of paper were investigated. For comparison purposes, the influence of an ethylene oxide treatment was also investigated. The papers chosen are representative of the types commonly found in an archive in the Netherlands. Irradiation with 10 KGy gamma rays for 1 hour accelerates the aging process by 50-100% (dependent on the type of paper). The acceleration of the aging process chiefly takes place in the initial period of aging. This will have a recurrent, cumulative effect with each new radiation. From the results of physical and chemical investigations of all types of paper fumigated with ethylene dioxide, it appears that there is no effect on the aging process of paper. From some results, it might even be carefully concluded that there is a slightly positive effect.