Historical materials made of paper are especially susceptible to fungal deterioration. Most of the fungi that associated with paper damage may be cellulolytic. The objective of this study was to detect the cellulolytic fungi from deteriorated old Chinese manuscripts from Central Library Universitas Indonesia. The cellulolytic assay used microcrystalline cellulose (MCC), a nearly pure cellulose and water insoluble form, and carboxymethyl cellulose (CMC), a water-soluble form. A total of 25 fungal strains from deteriorated old Chinese manuscripts were tested for the possibility to degrade MCC and CMC. The strains were grown in a single point inoculation on modified Czapek Dox Agar plates without carbon source, and 1% (w/v) MCC or 1 % (w/v) CMC was added as a sole carbon source. The results showed that fungal strains with cellulolytic activity formed halo formation after dyeing with Congo red. A total of 18 strains (72%) were able to use CMC, and 14 fungal strains (56%) were able to use MCC. Thirteen strains (52%) were able to use both MCC and CMC, and they were members of six genera (Anthostomella, Aspergillus, Cladosporium, Flavomyces, Penicillium, and Sarocladium). Six strains (24%) were not able to use both MCC and CMC. It was suggested that many of the fungal strains in this study employed the synergistic reaction of both exoglucanase and endoglucanase to degrade MCC, and endoglucanase (carboxymethylcellulase) to degrade CMC. The present study showed that the potential cause of the deterioration of old Chinese manuscripts were the cellulolytic fungal strains from the manuscripts.