In the last decades the textile industry has been criticised for exploiting and polluting the environment. Especially the production of mainstream textiles such as cotton has been found to create a great environmental burden. To overcome these environmental issues, sustainable textile options have emerged on the market. This thesis compares and discusses two case studies: the supply chains of conventional cotton and lyocell, a man-made regenerated cellulose fabric, which is praised for its sustainability. With material flow analyses both supply chains are investigated in order to evaluate and analyse their direct and indirect impact on the environment. The findings in this thesis show, that the cotton supply chain has an extremely high water demand, but a lower demand in chemicals compared to the lyocell supply chain. In total about 95 MJ/kg with non-renewable energy, 21400 litres of water and 3kg of chemicals are needed to produce 1kg of finished cotton fabric in this case study. The production of 1kg of finished lyocell fabric has an energy demand of 72 MJ/kg with non-renewable energy, 94 MJ/kg with renewable energy, a water demand of about 1500 litres and a chemical demand of about 19kg. Out of these chemicals 17.5 kg are reused and recycled within the supply chain. When energy sources are switched to renewable energy and partially self-produced energy, the lyocell supply chain produces 1.5 kg CO2 eq/kg of finished lyocell fabric. In contrast, the cotton supply chain in this case study produces 3.5 CO2 eq/kg of finished cotton fabric and thus releases more greenhouse gases and has a greater global warming potential. Despite the fact that natural resources are exploited for commercial purposes in both case studies, the lyocell case study is the more sustainable supply chain due to the conversion of waste into energy and due to the recovery and recycling of chemicals and wastewater in certain production processes. These sustainable actions lead to a minimum waste accumulation and therefore to reduced emission.