Samples of paper, parchment, and various types of microfilm were treated with products commonly used in paper conservation treatments, in disinfection, and in parchment restoration. Treated and untreated samples were inoculated with <i>Aspergillus niger</i> and contaminated samples were subjected to relative humidity of 65-100% and incubated for 20 weeks at 20°C. Results showed a decrease of microbial development after treatment with common products used in paper and parchment restoration. The degree of contamination in microfilm was lower in undeveloped film than developed film. Inhibition of microbial development in paper and parchment was noted after treatment with 4-chloro-3 cresol, o-phenilphenol (sic), pentachlorophenol, p-formaldehyde. Results of samples treated with ethylene oxide show that sterilized samples were more susceptible to attack by microorganisms and therefore ethylene oxide is not recommended for document conservation. Samples tested with gamma radiation show that no microbial growth was present, but a change in the physical and chemical properties of the support was noted. An increase in the mechanical strength of the paper after treatment with gamma rays was observed due to possible polymerization of the cellulose chains. Conclusions drawn from this study indicate the following: a decrease in microbial development in treated paper and parchment; barium hydroxide and calcium hydroxide used in deacidification are effective microbial inhibitors (although Bacillus and Actinomyces are resistant to it); cellulose acetate based microfilms are more susceptible to microbial growth than polyester ones; ethylene oxide is an effective biocide but if sterilized suports are subjected to high levels of temperature and relative humidity, their susceptibility to attack is greater than those not fumigated; gamma radiation is an effective alternative but slight aging of sterilized material must be taken into account.