Animal glue has been used to fix historical textiles on paper, wood panels, or other rigid support materials. It is often present in shrunk, cracked, rigid, and brittle form because of the aged condition artifacts and may not provide enough adhesion for effective support causing damage to historical textiles. The biotechnological application of enzymes seems to be a very promising approach in the restoration of historical objects. In this experimental work, undertaken with modern linen and silk fabrics, interesting results have been obtained for the removal of animal glue by using the protease enzyme from Aspergillus oryzae. An extensive study was done in the enzymatic activity and efficiency for the removal of the animal glue from the textiles, as well as the effects of this treatment on mechanical and optical parameters of the textile fibers. The effect of protease on fibers is measured by Fourier transform infrared spectral analysis, scanning electron microscope, the CIE-Lab values, ASTM method D5035, and XRD. The results showed that using protease in adhesive removal presented good results with a safe and a short treatment time when compared with the conventional methods. No significant changes on the linen and silk fabrics are observed. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012