Biodeterioration of textile materials is not confined to mildew and rotting of cellulosic products—micro-organisms interfere with processes such as water-jet weaving and they attack many textile auxiliaries including conventional sizing agents, fibre yarn lubricants, textile adhesives, back fillings, and latex emulsions, together with a variety of coated and laminated textile materials. Synthetic textile materials (with the exception of certain polyurethanes) and inherently resistant—nevertheless they are frequently susceptible to microbial spoilage because of the presence of the biodegradable processing and finishing agents. Unsightly mildew growth on synthetic textiles such as those derive from polyamides, polyester, polypropylene or polyacrylonitrile can be just as serious as the degradation of cellulosics because of the loss of aesthetic appeal. A review of textile biodeterioration is presented, along with methods of preventing microbial attack, detection of the presence of micro-organisms, and techniques for assessing propensity to mildew and biodeterioration and the efficacy of anti-fungal treatments.