In this book, the results of the chemical modification of cellulose fibres were presented, aimed at protecting the textile material against biodegradation. Namely, cellulose fibres are highly susceptible to microbial attack, resulting in worsened technological and applicable properties of textile products. This is a particularly crucial problem for textiles that are in use. The rate and degree of cellulose biodegradation is affected by several factors, among which the most important are the genera of micro-organisms and the environmental conditions needed for microbial growth.