In modern textile processing, environmentally friendly enzyme treatments are more and more replacing techniques that use concentrated chemicals and aggressive co-additives. Cellulase hydrolysis of cellulosic fabrics improves handle and drape, removes pills and gives color brilliance, and in denim finishing cellulases were introduced to replace pumice stones for creating the stone-wash effect. Until now no treatments using intensive cellulose degradation were established. In this thesis, viscose fabrics were pre-treated with liquid ammonia and NaOH solutions. The pre-treatments have been varied with regard to alkali concentration, time and drying conditions. Subsequently, the samples were subjected to cellulase hydrolysis. Microscope and SEM pictures were taken; weight loss, reducing sugar and protein content in solution, water retention value and tensile strength were determined. It was found that the activity of cellulases was increased for viscose and that short time alkali pre-treatment reduced tensile strength due to changes in the substrate. The drying and drying conditions (wet, line dry and freeze dry) had a great impact on the hydrolysis rate. A relation between velocity of protein loss in solution and changed water retention value was established. Weight loss of 80% of cellulose fabric was achieved within 4 hours of enzyme hydrolysis. This effect was also introduced into textile garment finishing. Local application by printing alkali-containing pastes permitted selective surface modification. Indigo ring-dyed denim fabric was used as an example. The intensified local degradation of the fibres on the surface of the fabric caused a higher contrast in the wash-down.