Man-made cellulose fibres have played an important role in the production of textile products for more than 70 years. The purpose of this study is to assess the environmental impact of man-made cellulose fibres. Life cycle assessment (LCA) was conducted for three types of fibres (i.e. Viscose, Modal and Tencel) produced by Lenzing AG. The functional unit is one tonne of staple fibre. The system boundary is cradle to factory gate. We compared the LCA results with other commodity fibres, namely cotton, PET and PP. Primary energy demand, water use, land use and the CML baseline impact categories were assessed. Sensitivity analyses were carried out to understand the influence of different allocation methods. In addition, three single score methods were introduced and applied. The LCA results show that four modern man-made cellulose fibre products, namely Tencel, Modal, Viscose (Austria) and Tencel (2012), have the lowest overall impact among all fibres studied. Viscose (Asia) has a higher overall impact than the other man-made cellulose fibres and is comparable to PET. Cotton is identified as the least preferred choice due to its high ecotoxicity impacts, eutrophication, water use and land use. The LCA results are influenced by the allocation methods applied; however, the ranking of all fibres does not change.